How Was Time Measured In Ancient China?

Before the evolution of the current standard way of measuring time, each traditional society had developed its method of measuring time. Although the various methods did not measure time accurately, they provided a useful estimation. This article will look at how time was measured in ancient China.

How did ancient China measure time


In ancient China, the heavenly bodies provided crucial information on time. The first recorded history of time measurement indicates that time was measured using a vertical pole of about 8 Chinese feet. The length of the shadow was used to determine the time. In 132 AD, the Eastern Han dynasty developed an astronomical clock called the water-transport celestial globe. The clock could tell time during the day and night. It was calibrated using the sun and the waning and waxing of the moon. In 1088 AD, China developed a complex time-measuring instrument called the Su Song Clock Tower. It measured time more effectively, and its calibrations depended on the sun.

Ancient Chinese time measurement

Ancient Chinese time measurement was no different from the current measurement. Time was measured by dividing the day and the night into intervals or units.


How many hours in a day were there in ancient China

Ancient China had two time-measuring systems that differed slightly in the number of hours per day. In the Han-er system, there were fifteen hours in a day. The hours were equal in length except for the last hour, which was equal to 10 hours of the modern day because it began from 8:00 PM to 6:00 AM.

The other significant system was the Eastern Hand to Ming System, which had a 12 hours day. Each hour was equivalent to modern-day two hours.


Ancient Chinese hours of the day

The hours of the day in the Han-er system were as follows, dawn between 6:00 AM to 7:00 AM, Morning light between 7:00 AM-8:00 AM, Daybreak 8:00 AM-9:00 AM, Early Meal 9:00 AM-10:00 AM, Feast Meal Before Noon 11:00 AM-12 Noon, Noon Noon-1:00 PM, Short Shadow 1:00 PM-2:00 PM, Evening 2:00 PM-3:00 PM, Long Shadow 3:00 PM- 4:00 PM, High Setting 4:00 PM-5:00 PM, Lower Setting 5:00 PM-6:00 PM, Sunset 6:00 PM-7:00 PM, Twilight 7:00 PM-8:00 PM, and Rest Time 8:00 PM-6:00 AM.

How did ancient China keep track of years?

Ancient Chinese kept track of years using a calendar based on astronomical phenomena. The Chinese counted the years of the emperor who was in charge. For instance, when there was a change of dynasty, they began their count again, until another change and they would begin to count again. Therefore, in ancient China, year one was the year a new dynasty began to rule.

Do China use a 12-month calendar?

Both the ancient and the current Chinese calendars are 12 months. The 12-month calendar was influenced by astronomical observations, not the Roman calendar. Most traditional societies had a 12-month calendar because it was mostly based on the waxing and waning of the moon.

Methods of Timekeeping have evolved to meet the needs of organizing work and life. Timekeeping methods include date planning and time planning. Date planning involves creating calendars to establish specific dates, while time planning focuses on describing time within a day. The description of time within a day serves as the foundation for calendar creation, and in turn, the methods used to construct calendars influence time planning. This article mainly discusses time planning.

In Chinese history, ancient Chinese people used various methods for timekeeping, including the Sixteen Shichen System, Ten Shichen System, Hundred Ke System, Twelve Shichen System, and the Sixty Points System introduced with Buddhism. Here, “shichen” refers to time periods.

Ten Shichen System

The decimal system was a natural choice, so early calendars and timekeeping used a decimal system. The Yin Yang Five Elements calendar belonged to the ten-month solar calendar, while the Ten Shichen System divided time into decimal increments. In the early usage of the Ten Shichen System, key natural phenomena, biological responses, and daily habits were selected as reference points to help people comprehend time. Later on, numerical codes such as celestial stems and earthly branches gradually replaced these references.

According to the “Book of Sui, Astronomical Treatise,” there were five time points during the day: morning, yu (around 9 a.m.), noon, afternoon, and evening. During the night, the five time points were named jia, yi, bing, ding, and wu. The five time points at night gradually transformed into additional time indicators during nighttime patrols, known as “wu gu” and “wu geng,” which continued until the end of the Qing Dynasty.

Hundred Ke System

The Hundred Ke System further divided the Ten Shichen System into one hundred equal ke. The Hundred Ke System may have originated during the Shang Dynasty. Excavated sundials from the Han Dynasty had markings for 69 possible ke. On the other hand, the demand for increased time measurement accuracy and the introduction of the Hundred Ke System led to the creation of the copper dripping vessel (dropping water into a vessel at a controlled rate) since dividing a circle into one hundred parts posed a significant challenge for manual craftsmanship.

During the Han Dynasty, the system was modified to include 120 ke, while the Southern Dynasty of Liang modified it to 96 ke or 108 ke. In the late Ming Dynasty, when European astronomical theories were introduced, the system was once again proposed as a 96 ke division.

Sixteen Shichen System

The Sixteen Shichen System emerged as a byproduct of calendar calculations. In the early stages of Chinese calendars, which transitioned from the Yin Yang Five Elements calendar to the Four Seasons Eight Festivals calendar, a fractional representation with 16 as the denominator appeared during the process of dividing a year into 12 months. Ancient Chinese recognized early on that a year consisted of 365 and 1/4 days, divided into 12 months of approximately 30 and 7/16 days each. The Sixteen Shichen System was a time division method developed to complement calendar calculations.

The “Huainanzi, Astronomical Instructions” records fifteen of the sixteen time points in the Sixteen Shichen System: morning brightness, dawn brightness, early morning brightness, early breakfast, late breakfast, corner-center, mid-center, little return, afternoon, great return, high pounding, low pounding, county (suspended) east, twilight, fixed twilight. However, it is difficult to consider the fifteen times from the “Huainanzi, Astronomical Instructions” as time points in the Sixteen Shichen System since there seems to be a considerable gap between morning brightness and fixed twilight, possibly suggesting a span of seven to eight hours during the night.

Twelve Shichen System

During the Western Zhou Dynasty, the concept of a year consisting of twelve months gradually stabilized in Chinese calendars. Comparing a day to a year, the Twelve Shichen System was used to divide a day into twelve segments, with fixed points (midnight) marking the transition between dates.

The Twelve Shichen System consists of twelve time points (starting points) known as the Twelve Shichen. In the Han Dynasty, they were named midnight, cockcrow, dawn, sunrise, eating time, corner-center, midday, mid-afternoon, afternoon, sunset, dusk, and midnight (human set). As people’s work and lifestyles became more diverse, the names gradually became less meaningful. Consequently, the Twelve Earthly Branches were adopted to represent the time points. The system starts with Zi (子) hour at 11 PM, Chou (丑) hour at 1 AM, Yin (寅) hour at 3 AM, Mao (卯) hour at 5 AM, Chen (辰) hour at 7 AM, Si (巳) hour at 9 AM, Wu (午) hour at 11 AM, Wei (未) hour at 1 PM, Shen (申) hour at 3 PM, You (酉) hour at 5 PM, Xu (戌) hour at 7 PM, and Hai (亥) hour at 9 PM.

During the Song Dynasty, mechanical timekeeping devices called “sichen timekeepers” appeared. These devices had rotating discs driven by gears, and a small wooden figure holding the hour plate would come into view. When the time was between two shichen, the displayed hour plate would not match the previous representation. Therefore, two reference points were used: the initial appearance of the hour plate and the hour plate in the correct position, known as “shichu” and “shizheng” respectively.

Moment Ke System, Striking System

The Moment Ke System combines the Twelve Shichen System and the Hundred Ke System. In early descriptions, it was expressed as “hour x ke,” meaning “x ke after the hour.” After the Song Dynasty, it changed to “initial appearance x ke, correct position x ke,” indicating “x ke after the initial appearance of the hour plate” and “x ke after the hour plate in the correct position.”

With the introduction of Buddhism, the Indian system of dividing a day into sixty points entered China and was combined with the Ten Shichen System, giving rise to the Striking System. Common expressions include “x chou y dian,” “x gu y dian,” and “x geng y dian.” The use of “chou” (筹) reflects the convenience of the Ten Shichen System in calculations compared to the Twelve Shichen System. The striking of drums and bells was used to mark time. The drum sound represented “geng,” while the bell sound represented “dian.” In ancient cities, curfews were enforced, and timing was crucial for opening and closing city gates. The time for opening the city gates in the morning was not as important, so people would usually pay attention to the frequent sound of bells. However, the time for closing the city gates in the evening required attention (otherwise, they would have to sleep on the streets inside the city), making the striking of drums (geng) a focal point. The difference in emphasis between “dian” and “geng” gave rise to the phrase “morning bells and evening drums.”

The duration of “一炷香” (yī zhù xiāng) can vary.

“One cup of tea,” “one meal,” and “one bag of tobacco” were units of time used by ancient people to estimate time. They referred to the time required to perform these activities. Generally, drinking a cup of tea and chatting in between takes about ten minutes. A meal typically takes twenty to thirty minutes. “One bag of tobacco” refers to the time it takes for a person to finish smoking a pipe of tobacco, which can vary from ten to fifteen minutes depending on the smoking speed.

In martial arts novels, we often come across the concept of “一炷香” (yī zhù xiāng), which refers to a unit of time. This method of timekeeping originated from the Buddhist practice of “Chanting Seven.” “Chanting Seven” originated around the Ming Dynasty when monks adopted a seven-day time unit for their practice. During each day, they focused mainly on meditation and did not attend morning, noon, or evening classes. Monks would use incense to measure time during their meditation practice, known as “sitting with incense,” and they would engage in physical exercises, known as “running with incense,” between each incense stick. In present-day Chinese Buddhism, monks still practice “Chanting Seven,” but they use clocks for timing, preserving the tradition of incense timing only in the names of the time schedule.

The duration of incense burning during “Chanting Seven” varies throughout the day, from 4 AM to 12 PM, with the number of incense sticks ranging from eleven to twenty-four. This variation is due to the differences in length, thickness, material, and manufacturing techniques of the incense sticks, which affect their burning speed. As observed, a certain brand of sandalwood incense stick, measuring 20 cm in length and 2 mm in diameter, burns for approximately 50 minutes indoors. Another brand of sandalwood incense stick, measuring 30 cm in length and 1.5 mm in diameter, burns for approximately 30 minutes under the same conditions. Thus, the duration of “一炷香” is not fixed.

Considering the circumstances of the time, this was a good method of time measurement. It was not affected by day or night, was convenient to carry, simple to make, and created a conducive atmosphere. The incense used during that time was handmade and had specific standards, similar to the present-day GB or ISO standards, and could not be made casually. The burning of an incense stick took about half an hour, equivalent to one hour in modern time. The night watchman who announced the time during the night shift also used incense to determine the time, so it was also called “更香” (gēng xiāng), meaning “striking incense.”

In ancient times, time was measured in various units: a year had twelve months, a month had five weeks, a week had six days, a shichen (2 hours) had eight ke, a ke (15 minutes) was divided into one hundred and forty-four fen (0.1 minutes), one cup of tea (10 minutes) had two incense sticks, one incense stick (5 minutes) had five fen, one fen (60 seconds) had six dantzhi (10 seconds), and one dantzhi equaled one moment (1 second).

According to the “Sengqilü” (Vinaya Pitaka), one moment is equivalent to one thought (念), twenty thoughts make one instant (瞬), twenty instants make one dantzhi (弹指), twenty dantzhi make one loyu (罗预), and twenty loyu make one xuyu (须臾). There are thirty xuyu in a day and night. Based on these calculations, xuyu equals 48 minutes, dantzhi equals 7.2 seconds, instant equals 0.36 seconds, and moment (刹那) equals one thought (念) or 0.018 seconds.

The character “柱” (zhù) in the context of “一柱香” (yī zhù xiāng) refers to “pillar” or “something resembling a pillar.” In the 6th edition of the Commercial Press Modern Chinese Dictionary, “柱” is explained as “a pillar” or “something resembling a pillar.” The 11th edition of the Xinhua Dictionary defines “柱子” (zhùzi) as “an upright supporting component in a building, often made of wood, stone, etc.” Common phrases include “偷梁换柱” (tōu liáng huàn zhù), “顶梁柱” (dǐng liáng zhù), and “擎天柱” (qíng tiān zhù), all of which refer to supporting wooden components. In the idiom “胶柱鼓瑟” (jiāo zhù gǔ sè), “柱” refers to a short piece of wood used to adjust the sound of a musical instrument. In essence, “柱” serves as a supportive wooden structure and does not function as a quantifier.

The character “炷” (zhù) has three meanings in both the 6th edition of the Commercial Press Modern Chinese Dictionary and the 11th edition of the Xinhua Dictionary. It can refer to “wick,” specifically to “burn incense,” or it can be used as a measure word for lit incense sticks. For example, in the Tang Dynasty poet Han Wo’s “Autumn Village,” there is a line that says, “绝粒看经香一炷,心知无事即长生” (jué lì kàn jīng xiāng yī zhù, xīn zhī wú shì jí cháng shēng), which uses “一炷香” to indicate time. Similarly, in Su Shi’s “Two Poems on Writing the Twin Bamboo-Zen Room,” there is a line that says, “羡师此室才方丈,一炷清香尽日留” (xiàn shī cǐ shì cái fāng zhàng, yī zhù qīng xiāng jìn rì liú), which also uses “一炷香” to represent a duration of time. In the Tang Dynasty poet Xu Hun’s “Autumn Evening Banquet at Li Shi’s Residence,” the line “烛换三条烬,香销十炷灰” (zhú huàn sān tiáo jìn, xiāng xiāo shí zhù huī) indicates the length of time.

one cup of tea

The duration of “一盏茶” (yī zhǎn chá), which means “one cup of tea,” is approximately fifteen minutes. In ancient times, when precise timekeeping devices were not available, people used common activities to estimate time. “一盏茶” refers to a specific type of teacup with a saucer and a lid, designed to drink tea slowly and prevent the tea leaves from escaping. The time it takes for a cup of tea to be served and cooled down can vary. In summer, it might take around 15 minutes, while in winter, it could be less than 10 minutes.

a pot of wine

The time for “一壶酒” (yī hú jiǔ), which means “a pot of wine,” is one “时辰” (shí chen), equivalent to two hours.

one meal

The time for “一餐饭” (yī cān fàn), meaning “one meal,” is half a “时辰,” approximately one hour. It is worth noting that in modern times, people usually spend around half an hour for a meal.

a bag of cigarettes

The time for “一袋烟” (yī dài yān), referring to “a bag of cigarettes,” is approximately one minute. In the past, people used handmade smoking pipes, and the process of smoking involved taking out the pipe, retrieving tobacco from a pouch, placing a small amount of tobacco in the pipe, lighting it, taking a few puffs, and then discarding the burnt tobacco. This entire process would take about one minute.

In ancient China, time divisions within a day were often determined by various timekeeping devices. The earliest time indicators were based on the position of the sun, such as “日初出” (rì chū chū) for sunrise and “日中” (rì zhōng) for midday. However, these terms were used to identify specific moments rather than units of time.

The earliest recorded time measurement system was the “百刻制” (bǎi kè zhì), where a day was divided into one hundred “刻” (kè), with each “刻” being approximately 14.4 minutes. This system was based on the use of a water clock called “刻漏” (kè lòu), which consisted of a dripping vessel and a graduated floating ruler. As the water dropped, the ruler displayed the volume of water and indicated the passage of time. Eventually, the twelve “时辰” (shí chen) system, which divided a day into twelve equal segments, merged with the “百刻制.”

During the Qing Dynasty, the introduction of Western clocks led to the combination of the twenty-four-hour system with the “百刻制,” resulting in one hour being divided into four “刻” and a day consisting of ninety-six “刻.” Ultimately, the twenty-four-hour system replaced the “百刻制.”

The “十二时辰制” (shí èr shí chen zhì) and the “二十四时辰制” (èr shí sì shí chen zhì) were originally based on the position of the sun and were determined by dividing the sundial into twelve or twenty-four parts. These systems used names derived from the Chinese zodiac, directions, and celestial stems to denote each time segment. Although widely adopted during the Southern and Northern Dynasties, the accuracy of these systems was lower compared to the “百刻制.”

Apart from the official time measurement systems, ancient Chinese people also used various vocabulary to express time in daily life. Due to the less precise requirements for time in their activities, these terms often referred to vague periods.

One “geng” is how many hours

When people watch TV and shout “The air is dry, be careful with the candle!” and other prompts. The folk legend about the rooster’s crow: “Fire during the first geng, thief during the second geng.” It means that if a rooster crows during the first geng, there will be a fire, and if it crows during the second geng, there will be a thief (it is said that it is 80% accurate). So how many hours is one geng in ancient times?

In ancient China, the four units of time measurement were shi (hour), geng (watch), dian (moment), and ke (moment). Shi, also known as shichen (hour).

In ancient times, people divided the day into several time periods based on the natural lighting conditions. For example, the period just before dawn was called meidan (dawn breaking), sunrise was chen (morning), when the sun was at its zenith was rizhong (midday), after sunset was huanghun (twilight), and nighttime was called xiao or xi, and so on. Later, the day and night were divided into twelve equal parts, known as the twelve shichen. The complete names of the twelve shichen are recorded in “Zuo Zhuan” by Du Yu in the fifth year of Duke Zhao. They are: midnight, rooster crowing, dawn, sunrise, breakfast, yu zhong, midday, afternoon, afternoon snack, sunset, dusk, and bedtime.

During the reign of Emperor Wu of Han, the twelve Earthly Branches were used to represent the twelve shichen, replacing the previous midnight, rooster crowing, dawn, etc. Each shichen was further divided into two-hour periods, such as zishi (midnight) being divided into zichi and zizheng, choushi (early morning) being divided into chouchu and chouzheng, and so on. This way, the twelve shichen of a day were subdivided into twenty-four hours, exactly the same as the modern usage.

Tianse fa (lighting conditions) and dizhi fa (Earthly Branches method) are two common methods of timekeeping in ancient poetry and literature. For example, in the poem “The Peacock Flies Southeast,” it says, “The rooster crows, weaving never ceases.” And “After the desolate twilight, silence settles in.” In the poem “Lost at Jiating,” it says, “The Wei soldiers were trapped from the chenshi (early morning) until the xushi (evening).” In the poem “Jingyang Hill,” it says, “The guests can pass the hill during the sishi (late morning), wushi (noon), and weishi (early afternoon) periods.” In the poem “Ji Mei Wen,” it says, “If I return home at the weishi (early afternoon) hour, and you breathe your last at the chenshi (early morning) hour.” In the story “The Gathering of Heroes and Jiang Gan’s Cunning Plan,” it says, “They marched from the sishi (late morning) hour straight until the weishi (early afternoon) hour.”

The ancient Chinese also divided the nighttime into geng and dian. In ancient China, the night was divided into five periods, and a drum was beaten to announce the time, hence it was called wugeng or wugu (five geng) or wuye (five nights). One geng is also equivalent to two modern hours. Starting from 7 PM, the first geng refers to the period from 7 PM to 9 PM, the second geng refers to 9 PM to 11 PM, the third geng refers to 11 PM to 1 AM the next day, the fourth geng refers to 1 AM to 3 AM, and the fifth geng refers to 3 AM to 5 AM. In the poem “The Peacock Flies Southeast,” it says, “Looking up and facing each other, they crow until the fifth geng every night.” In the story “The Gathering of Heroes and Jiang Gan’s Cunning Plan,” it says, “Lying on the pillow and listening, the drums in the army beat the second geng.”

Furthermore, one geng was further divided into five dian. In ancient times, one dian was equivalent to 24 minutes in modern times. For example, when ancient people said “san geng er dian” (three geng two dian), it referred to 11:48 PM. In the past, there was a Drum Tower in the Forbidden City in Beijing. After twilight, the Drum Tower would ring 108 times to indicate the start of the geng period. Cities such as Nanjing, Xi’an, Tianjin also had Drum Towers, where the night watchman would beat the drum according to the indicated time on the Drum Tower to announce the time, preserving the old tradition. In ancient times, one day and night were divided into 100 ke, and one ke was equivalent to 14 minutes and 24 seconds in the present time. The expressions “qingke” and “shaoqing” in ancient language both refer to a very short period of time.

In the Han Dynasty, there were four shifts for the palace duty personnel, the start shift, three handovers, and the end shift, which was called “wugeng.” Therefore, there were five geng in one night, and the time between two geng was 2.4 hours. Xuchu yike was the first geng, Huai chusanke was the second geng, Zishi zheng was the third geng, Chou zheng erke was the fourth geng, and Yin zheng sike was the fifth geng.

午时三刻 is equivalent to 12:45 PM in modern time.

In ancient China, the day was divided into 12 time periods known as shichen. Each shichen was further divided into two parts, known as “shi chu” and “shi zheng,” and each part was divided into four smaller parts called “chu ke” and “zheng ke.” Therefore, each shichen was divided into eight ke, which provided a more precise time measurement.

The term “午时” refers to the period from 11:00 AM to 1:00 PM, which is the time when the sun is at its zenith and the yang energy reaches its peak. According to Taoist beliefs, during this time, most animals rest or lie down, except for horses, which have a habit of standing even while sleeping. Hence, the horse is associated with the hour of “午时.”

Within the hour of “午时,” there are four “刻” (ke), and “午时三刻” specifically refers to the third ke within the hour of “午时.” Therefore, “午时三刻” corresponds to 12:45 PM.

It’s important to note that the concept of “刻” has evolved over time. In ancient times, one 刻 represented half an hour (30 minutes), whereas today, it represents a 15-minute interval. So, while in ancient times “午时三刻” referred to 12:45 PM, in modern usage, it would be understood as 11:45 AM.

However, it’s worth mentioning that historically, during the Ming Dynasty, “午时三刻” was the designated time for executing prisoners because it was believed that the yang energy was at its strongest, suppressing the restless spirits of the condemned individuals. This practice aimed to reduce the suffering of the prisoners. The significance of the yang energy being at its peak during this time was based on the longitude of the capital city. In the case of Beijing, which was the capital during various dynasties, including the Ming Dynasty, the longitude was considered, and the execution time was set accordingly. However, due to the longitude difference between Beijing and Xi’an (another significant city in ancient China), which is approximately 45 minutes, the actual moment of the sun’s zenith may differ slightly. Therefore, to determine the exact time when the yang energy is at its peak, the longitude of Xi’an is often considered.

In summary, “午时三刻” corresponds to 12:45 PM in modern time. However, it’s important to consider historical context and regional variations when interpreting ancient time measurements.

a moment is hours

In ancient China, the time unit “刻” (ke) was used for timekeeping. The concept of “刻” dates back to the Zhou Dynasty and was based on the ancient water clock, known as the “漏壶” (louhu). The louhu consisted of a copper vessel with a small hole at the bottom. Water would drip from the hole, and the time was measured by the gradual descent of the water level, revealing markings on a scale attached to the vessel. A complete day and night would correspond to the dripping of the water to the last drop, and the scale markings indicated the passage of time in “刻.”

Around the time of the Western Zhou Dynasty, a day and night were divided into 100 “刻,” with each “刻” being approximately 14.4 minutes. During the Han Dynasty, in addition to the hundred ke system, time was also measured based on the position of the sun. The Sui and Tang Dynasties introduced the twelve shichen system, which divided the day into twelve equal parts. The hundred ke system and the twelve shichen system were used concurrently, and a unique timekeeping method called “更” (geng) was used during the night. The night was divided into five “更,” with the duration of each “更” varying depending on the length of the night.

It was not until the late Ming Dynasty and early Qing Dynasty that mechanical clocks from the West were introduced to China. The Chinese gradually adopted a 24-hour timekeeping system, but the twelve shichen system remained in use, with each shichen representing two hours. To align with the 24-hour system, the ancient hundred ke system evolved into the ninety-six ke system, with each shichen divided into eight ke and each hour divided into four ke. Thus, each ke represented 15 minutes, resulting in a total of ninety-six ke in a day, consistent with the internationally recognized timekeeping system.

The term “小时” (xiaoshi) derived from “大时” (dashishi), which was used in ancient China to refer to one shichen, equivalent to two hours in modern time. When clocks and watches were first introduced to China, one shichen was called “大时” (dashishi), and the new time measurement of one hour was called “小时” (xiaoshi). Over time, with the popularity of clocks and watches, the term “大时” gradually disappeared, and “小时” continued to be used to refer to one hour.

Therefore, “一刻” (yī kè) refers to a duration of 15 minutes. It does not represent a specific number of hours, but rather a smaller division of time within an hour.

one “时辰” (shí chén)

In ancient times, one “时辰” (shí chén) is divided into 8 “刻” (kè), and each “刻” is equivalent to 15 minutes in modern time. The ancient Chinese timekeeping system used the twelve Earthly Branches to represent the 12 “时辰” throughout a day and night cycle. Here are the corresponding time periods:

子时 (Zi Shi) – 23:00 to 01:00

丑时 (Chou Shi) – 01:00 to 03:00

寅时 (Yin Shi) – 03:00 to 05:00

卯时 (Mao Shi) – 05:00 to 07:00

辰时 (Chen Shi) – 07:00 to 09:00

巳时 (Si Shi) – 09:00 to 11:00

午时 (Wu Shi) – 11:00 to 13:00

未时 (Wei Shi) – 13:00 to 15:00

申时 (Shen Shi) – 15:00 to 17:00

酉时 (You Shi) – 17:00 to 19:00

戌时 (Xu Shi) – 19:00 to 21:00

亥时 (Hai Shi) – 21:00 to 23:00

Each day and night is divided into 100 “刻” in the ancient timekeeping system. This was often measured using a water clock called the “漏壶” (lòu hú). One day and night is equivalent to 24 hours or 100 “刻,” so each hour contains 4 “刻,” and each “时辰” contains 8 “刻.” In modern time, each “刻” is approximately 14.4 minutes.

Below the “刻,” there is the unit called “字” (zì), which is still used in the Cantonese dialect spoken in Guangdong and Guangxi regions. For example, “下午三点十个字” means “three o’clock and ten ‘字'” and indicates 15:50 in modern time. The exact subdivisions below “字” are not well-documented, but according to the “Lu Li Zhi” section in the “Sui Shu” (Book of Sui), the unit below “字” is called “秒” (miǎo), which translates to “second.” The unit below “秒” is called “忽” (hū), but the conversion rate is not explicitly stated, with the description likening it to the fineness of a thorn or the finest spider silk.

Ancient Chinese Timekeeping Method

The invention of ancient Chinese timekeeping devices dates back to no later than the Warring States period (476-222 BCE). There are two main types of timekeeping devices based on mechanical principles: those that utilize fluid mechanics, such as the clepsydra (water clock) and the later invention of the hourglass, and those that employ mechanical transmission mechanisms, such as the armillary sphere and the water-powered astronomical clock.

In addition, one of the oldest timekeeping devices in China is the sundial, which operates based on astronomical principles, often using the direction of the sun’s shadow to determine time.

The earliest timekeeping instruments used by humans relied on the length and direction of the sun’s shadow. The device used to measure the length of the shadow is called a “guibiao” or sundial, used to measure midday, determine the seasons, and identify directions. The term “rihui” or sundial refers to the device used to measure time. Together, these instruments are referred to as sundials.

There are records of the use of sundials during the Shang Dynasty in China, which existed from 1300 to 1027 BCE, as evidenced by oracle bone inscriptions. The poem “Ding Zhi Fang Zhong” from the Book of Songs describes the use of a sundial: “Determined in the center, created in the Chu palace. Measured by the sun, created in the Chu chamber.” The exact recorded use of the sundial dates back to 659 BCE.

Sundials, including the guibiao, lose their functionality on cloudy days or during the night. To address this, people invented timekeeping devices such as the water clock, hourglass, oil lamp clock, and candle clock.

Guibiao (Sundial):

Also known as a “rihui” or “rigui.” The “biao” in guibiao refers to a vertical pole or stone pillar erected on the ground, while the “gui” is a horizontal stone slab extending northwards from the base of the sundial. When the sun reaches its southernmost point, the shadow falls on the gui. By measuring the length of the shadow, one can calculate the timing of the winter solstice, summer solstice, and other solar terms. The longest shadow indicates the arrival of the winter solstice, while the shortest shadow indicates the arrival of the summer solstice. The guibiao is the oldest and most familiar astronomical instrument in China.

Clepsydra (Water Clock):

Also known as a “louluo” or “louhu.” There are mainly two types of clepsydra: the overflow type and the constant flow type. Early clepsydra devices were mostly of the overflow type, where water flows out from the side of the water vessel, and a floating arrow on the water surface inside the vessel descends along with the water level, indicating the time based on calibrated marks. Later, the constant flow type was invented, where water is continuously poured into a separate vessel at a constant rate, and a floating arrow on the water surface inside the vessel rises, indicating the time and improving the accuracy of timekeeping.

To achieve a constant flow rate, the water level in the water vessel must be maintained constant. Additionally, the cross-sectional area of the water pipe used to fill the separate vessel must be fixed. The water pipe utilizes the principle of “ke wu” or siphoning, which facilitates adjustment and repairs. There are two methods to maintain or approximate a constant water level, both depicted in Yang Jia’s “Liujingtu” (Illustrated Classic of the Six Texts), published in 1153. The “Tang Dynasty’s Lu Cai (approximately 600-650 CE) Determination” clepsydra depicted in the illustration adds a few compensatory vessels above the water vessel, while the “Yan Su’s (1030 CE) Determination” clepsydra uses an overflow method with a depth of four inches. The excess water flows from a water pitcher (lower reservoir) through a bamboo pipe into a reducing vessel. The clepsydra invented by Yan Su is known as the lotus clepsydra, which gained popularity during the Northern Song Dynasty.

The earliest record of the clepsydra can be found in the “Zhou Li” (Rites of Zhou). The oldest preserved clepsydra artifacts discovered to date are from the Western Han Dynasty, with a total of three bronze clepsydras, all of which are of the overflow type. The most complete and well-documented surviving clepsydras are of the constant flow type. One is housed in the Chinese History Museum in Beijing, created in the third year of the Yuan You reign (1316 CE) of the Yuan Dynasty. The other is in the Palace Museum in Beijing and was manufactured during the Qing Dynasty.


Due to the freezing of water in winter, an alternative method using flowing sand was developed for hourglasses. The “Five-wheel Hourglass” was created by Zhan Xiyuan during the early Ming Dynasty, as recorded in the “Astronomy” section of the “Ming Shi” (History of Ming). Later, Zhou Shuxue enlarged the sand outlet to prevent blockage and used six wheels instead. Song Lian (1310-1381) documented the structure of the hourglass in his collection of essays titled “Collected Works of Song Xueshi.” He provided dimensions of the components and the number of teeth on the reduction gears, mentioning that the axle end of the fifth wheel has no teeth but is equipped with a measuring disc for indicating time.

Water-powered Armillary Sphere

Ancient texts mention the construction of an armillary sphere during the reign of Emperor Wu of Han (140-87 BC) by Luo Xia Hong and Xian Yu Wang, but they do not provide details about its structure.

The “Book of Jin” in the “Astronomy” section records that Zhang Heng (78-139 AD) of the Eastern Han Dynasty created an armillary sphere driven by flowing water. It is said that the instrument accurately indicated the appearance and disappearance times of celestial bodies, consistent with astronomical observations.

The “New Book of Tang” in the “Astronomy” section provides a detailed description of the armillary sphere designed by Monk Yi Xing and Liang Lingzan in the 13th year of the Kaiyuan era (725 AD) of the Tang Dynasty. The instrument featured two circular rings, one for the sun and one for the moon, driven by a water wheel. The celestial globe completed one rotation per day, while the sun ring completed 1/365th of a rotation per day. The instrument also included two wooden figures that played drums and bells, respectively, marking the hours. It was a wooden structure with a narrow upper section and a broad lower section.

The water-powered armillary sphere relied on hydraulic power to simulate celestial motions and measure time. It improved upon the design of Zhang Heng in the Han Dynasty by using water to drive its rotation. In addition to demonstrating the movement of stars, it also represented the rising and setting of the sun and moon. It was more intricate and sophisticated than Zhang Heng’s water-powered armillary instrument. When the water-powered armillary sphere was completed and placed in front of the Wucheng Hall, it amazed the officials and scholars who witnessed it. They praised its exquisite craftsmanship, precise determination of lunar months, and accurate time reporting.

Notably, the water-powered armillary sphere also featured two wooden figures (related to the archaeological site “Shangzhou Copper Buddha Shrine”) driven by gears. One figure automatically played drums every ke (ancient unit of time representing one day and night divided into 100 parts), while the other figure struck a bell every chen (equivalent to two modern hours). These two wooden figures can be considered ancient robots created using mechanical principles. It was a remarkably ingenious timekeeping device and the earliest mechanical clock device in the world, preceding the appearance of the Wells Cathedral clock in the West in 1370 by six centuries. This fully demonstrates the ingenuity of ancient Chinese laborers and scientists.

Although the water-powered armillary sphere ceased functioning after a period of use due to the stiffness of the copper and iron parts, it earned the inventors Monk Yi Xing and Liang Lingzan their place in history for the invention of the astronomical clock. Dr. Joseph Needham, a renowned British historian of science and technology, stated in Volume IV of “Science and Civilisation in China” that the parallel linkage mechanism invented by Monk Yi Xing and.

Water-Powered Astronomical Clock

The Water-Powered Astronomical Clock, also known as the Water-Powered Armillary Sphere, was constructed by Su Song, Han Gonglian, and others in the third year of the Yuan You period of the Northern Song Dynasty (1088). They documented its design and components in the book “New Treatise on Astronomical Clockwork” during the initial years of the Shaosheng period (1094-1097).

This clock stood over three zhang and five chi tall (approximately 10 meters) and was about two zhang and one chi wide (approximately 6.7 meters). It was a wooden structure with a narrow upper section and a broad lower section. The lower part of the clock contained a water-lifting mechanism. A human-operated water wheel, driven by a river cart, lifted water to the upper wheel and lower wheel (cylindrical cart). The water was then delivered to the Heavenly River (water trough) and poured into the Celestial Reservoir (water storage tank). A water vessel in the middle of the clock maintained a constant water level, and water flowed at a steady rate through a water pipe of specific cross-section into the receiving vessel on the escapement wheel (water wheel), driving its rotation. The escapement wheel, in turn, powered the day and night mechanism, celestial globe, and celestial globe armillary.

The Water-Powered Astronomical Clock featured a complex system of gear transmission. Above and around the escapement wheel, there was a device called the “Tianheng” (Celestial Balance), which was a significant invention in the history of timekeeping mechanisms, following the earlier invention of the escapement. It converted the continuous rotational motion of the escapement wheel into intermittent rotational motion.

The “New Treatise on Astronomical Clockwork” does not include a diagram of the Tianheng device with the escapement wheel and the water vessels mounted on it. The textual description in the book is brief: “The escapement wheel has a diameter of one zhang and one chi, with seventy-two spokes planted in two concentric circles on a hub, forming thirty-six spokes. Each spoke holds one water vessel, making a total of thirty-six vessels. Each vessel is one chi long, five cun wide, and four cun deep. Iron teeth are placed on the side of the vessel to engage the Tianheng mechanism.”

Therefore, there have been different speculations about the structure of the water vessels, particularly their working principles. One proposed scheme suggests the use of tiltable water vessels. When the water vessels on the circumference of the escapement wheel did not accumulate enough water weight, the left celestial lock blocked one spoke of the escapement wheel, preventing its rotation. When the water weight reached a certain threshold, and the weight of the water vessels exceeded the balance provided by the escapement wheel, the water vessels tilted downward around the axis. The iron teeth on the side of the vessels pressed against the gear and caused the release lever to descend, lifting the celestial lock and left celestial lock, allowing the escapement wheel to rotate. After one water vessel passed, the gear and release lever rose again, causing the celestial lock and left celestial lock to descend, blocking the next pair of spokes on the escapement wheel. The role of the right celestial lock was to prevent the escapement wheel from bouncing back during rotation. The celestial weight and escapement weight were two balancing counterweights. The celestial weight balanced a portion of the gravity of the left celestial lock and release lever, allowing adjustment of the sensitivity of the Tianheng mechanism. The escapement weight adjusted the water volume needed by the water vessels during one pair of spokes’ rotation on the escapement wheel, determining the interval of the intermittent movement and thus correcting timing errors.

Clepsydra of the Great Ming Dynasty

In 1276, during the Yuan Dynasty in China, Guo Shoujing created the Clepsydra of the Great Ming Dynasty. It was powered by water and employed a complex system of gears and a sophisticated cam mechanism to drive automaton figures that struck bells and gongs to indicate the time.

how did ancient China tell time

In ancient China, the traditional way of telling time was represented by the idiom “暮鼓晨钟” (mù gǔ chén zhōng), which referred to the evening drums and morning bells. The drum tower (鼓楼) and bell tower (钟楼) served as the timekeeping centers in ancient cities.

According to the ancient customs, the night was divided into five “geng” (更), with each “geng” equivalent to two hours, similar to the present-day concept of an hour. The first “geng” (from 19:00) was called the “ding geng” (定更) or “qi geng” (起更), the second “geng” (21:00) was the “er geng” (二更), and so on.

To ensure accurate timekeeping, the bell and drum towers were equipped with four bronze clepsydras: “Tian Di” (天地), “Ping Shui” (平水), “Wan Fen” (万分), and “Shou Shui” (收水). In the center of each clepsydra, there was a copper instrument called “rao” (饶), which was mechanically operated to strike and announce the time at each moment.

During the night, there were people known as “打更人” (dǎ gēng rén), responsible for telling time through sound by striking certain objects. These timekeepers ensured that daily work and officials’ schedules were not delayed during the nighttime.

The bell tower and drum tower were essential timekeeping centers in ancient walled cities. The sound of evening drums marked the start of a day’s work, while the morning bells signaled the end of a labor-intensive day. Each night was divided into five “geng,” with each “geng” approximately two hours long.

The saying “三更半夜” (sān gēng bàn yè) in Chinese folklore refers to the time around 11 pm, which is considered the middle of the night. The striking of the bells and drums was a crucial daily event, and skilled timekeepers knew how to perform this task effectively. The timing and frequency of striking the bells and drums followed a specific rhythm, creating a melodic and distinct sound that resonated throughout the city.

In ancient times, timekeepers used various methods to know the time accurately. For instance, during the Qing Dynasty, they burned timekeeping incense, and the burning rate determined the time. In the Song Dynasty, they used “刻漏” (kè lòu), a kind of water clock, for timekeeping. Mastering the art of timekeeping was vital for timekeepers, as any mistake in announcing the time could lead to severe consequences.

The culture of the bell and drum towers and the tradition of “打更” (dǎ gēng) have become an integral part of traditional Chinese culture. Today, the idiom “暮鼓晨钟” and the concept of “打更” continue to hold historical and cultural significance in China.

dǎ gēng rén


Time measurement is one of the most ancient practices in China. The desire of the ancient societies to know the time led them to develop difficult time-measuring tools. Keeping track of time was as significant then as it is now. The effort of ancient society has led to the development of modern-day time measurement units and tools.   

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