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Decocting Chinese Herbs, Herb Doses, & Traditional Unit Conversion Rates

Decocting Chinese Herbs, Herb Doses, & Traditional Unit Conversion Rates

By Chad Ryan

Decocting Chinese Herbs

Boiling raw herbs into a decoction is a potent, easily digestible and aesthetically pleasing way to enjoy your herbal medicine. On the other hand, it takes time, and fuel; and it takes more time and fuel to reheat successive doses after the initial cooking. Some practitioners go so far as to recommend boiling and straining herbs three times in order to really extract the maximum value out of the solid material in the pot. Another more energetically efficient way of making the most of expensive ingredients is in fact to soak them in just enough water to saturate them, for twenty minutes, prior to placing them above a flame, and then adding more scalding water from the kettle. Even just running a bit of cool water over and around the dregs after boiling and straining, as if to wash the left over matter, will immediately provide an additional visibly tinted run-off.

The quantity of water used for boiling herbs should be substantial to saturate the dry herbs during the boiling period. As long as the herbs are boiled for an adequate length of time while they are submersed in the liquid, they need only then be divided by the specified number of doses per bag used, to provide the appropriate quantity of medicinal material per dose. If you used more water, then the volume in each dose will be larger, but the concentration will equally be more dilute. Nonetheless, there is a distinct disadvantage in using more water than necessary to boil your herbs, and that is you will have to consume more water just to take your medicine, and this may be arduous if you don’t like the taste. You may thus aim to be left with one small cup, or 150mL per dose, on consumption.

Your herbs should normally be boiled for 25 minutes from the time that the water starts bubbling, although certain decoctions may be boiled for longer or shorter periods. Some individual herbs should also be boiled for more than twenty-five minutes, and some for much less than twenty-five minutes, and the practitioner is responsible for providing this information, which for convenience can be separated from the bulk of the formula when dispensed.

Often one bag of herbs can be decocted to produce three doses. Therefore, you can be more economical by preparing more than one bag at once for the upcoming week, if the herbs are refrigerated after decocting. If the herbs are kept at room temperature, they can be kept for two days following decoction. Ideally, herbs will be kept in a sealed container. If the ingredients have protein, starch or sugar, they can also more rapidly deteriorate, and should the smell of the decocted liquid have changed since the time of boiling, or bubbles have appeared on the surface of the liquid, then the decoction should be discarded and not consumed1.

As Chinese herbs should be drunk warm to benefit the spleen energy so as to maximise their uptake, successive doses will need to be reheated. Adding some boiling water from the kettle to the dose will achieve this end, while boiling the entire dose itself once more will denature proteins should you be worried about the formation of bacteria or viruses.

Powders & Granules

When boiling herbs, don’t eat the solid matter itself after cooking. This is called the dregs, and it can be dispensed of as food for your garden. Sometimes however, medicinal herbs are eaten when prepared in alternative ways, such as in the form of powders or granules. Importantly, the dose, when an herbal formula is converted into powder is not as large. One reason is surface area, and thus, should an herb be purposely crushed prior to being added to a formula which is to be boiled, only one to two thirds the regular quantity needs to be used. Nonetheless, it is implied that a herb that is to be crushed prior to boiling, will still be separated from the liquid during the straining process.

When a formula is consumed entirely as a powder or as granules however, the herbal matter is indeed consumed, either by mixing it with hot water as a tea, chewing it and then washing it down with a swig of water, or swallowing it whole after it was been constructed into a pill. Hence the dose quantity is less again in comparison to the traditional method of decocting whole herbs.

Granules are a relatively modern prepared form of herb, which began being produced by factory owners in Japan in 19763, differing from powders in that they are produced in a big vat which extracts the essence of the herbs by boiling them before solidifying them once more. As the readily soluble exponents of an herb, it is intended that granules are to be swallowed with the water when consumed as a tea. Many practitioners appear to have settled on using one fifth of the dry weight when prescribing granules instead of the standard fresh herbs that are used in decoction by boiling2.

Powders by contrast are simply the raw herb ground finely. The toxicity level of every individual herb is a particularly important consideration when consuming this more traditional form of medicine, which may also be constructed into pills; because powder has not been cooked at any stage of its processing. Hence, from one fifth up to one eighth or one twentieth of the dose of raw herbs may be the recommended dose when using herbs in the powdered form2.

Converting Traditional Measurements

When traditional Chinese units had been used instead of modern metric units, the 斤 jīn had equated to sixteen 兩 liăng, while a single liăng had equated to ten 錢 qián, and one qián to ten 分 fēn. In English, the Chinese weight units of a jīn and a liăng are respectively know as a catty and a tael. In mainland China one jīn has nowadays been standardised to 500 grams, so one qián according to the traditional ratio would be 3.125 grams. In Taiwan, because one jīn is now 600 grams, one qián would according to traditional proportions be 3.75 grams5. In the year 1959 however, the official modern units were developed, which state that one catty is now just ten tael, so one teal is now 50 grams, one qián 5 grams, and one fēn 0.5 grams. If you are referring to a classical text however, you should not only treat one catty to mean sixteen tael, but also you should take note of the time in which the prescription was written, in order to discern the exact doses that are being inferred, as the standard reference weights have varied over time.

The Shāng Hán Lùn and the Jīn Guì Yào Lüè were written around the time of the eastern Hàn dynasty, from 25 CE until 220 CE. One jīn according the Shining Harmony Grand Minister of Agriculture’s Copper Weight of the time was standardised at 250 grams, and therefore one liăng at 15.6 grams. While these conversion rates may be applied when reading recipes from these original classic texts of this time, some pundits think that a catty in the eastern Hàn dynasty referred to about 220 grams and a tael therefore 13.8 grams, because of the coexistence of two other relics dating from that era: those being a 333 gram copper weight engraved as weighing one catty and eight taels, and a 354 gram stone weight engraved as weighing one catty and ten taels. Proponents of this second line of thought may convert ancient formulas into the metric system at this slightly decreased ratio. To confuse matters further, Japanese practitioners can tend to prefer to follow a description from a school in Kojima that asserts one 铢 zhū as equates to both one 24th of a tael by definition and to 10 grains of a variety of millet called 秬黍 jùshŭ according to the ancient weight ratios of Shénnóng the divine farmer. The weight of a tael according to this rationale is only 1.30 to 1.42 grams, which radically alters the actual weight of this unit4.

The variance in weight of the tael over the course of Chinese history may roughly be traced over time: from the fifth century BCE to 207 BCE as 15.8 grams; then until 589 CE as 13.8 grams; from 581 to 619 CE as 13.8 grams if it was a small tael, and as 41.3 grams if it was a big teal (this type of teal was more of a “big deal”); as 41.3 grams from the conclusion of that period until 907 CE (the 41.3 gram tael was no longer such a big deal); as 40 grams from 960 CE until 1279 CE; from 1368 CE until 1644 CE as 36.875 grams; from that end until 1928 CE as 37.3 grams; and from 1929 until 1959 as 31.25 grams. Naturally, the weight of the caddy can always be derived as being equivalent to 16 teals of the relevant era, and one qián as one tenth of a teal.

Over this same lengthy period of history in China, there has furthermore existed another exponential series of units for measuring volume, rather than mass, and prescriptions that have small spherical herbs among their components appear for practical purposes to have traditionally opted to list the quantity required of such ingredients according to this alternative set of units. The most enduring units of volume between the warring states period and now are the following: the 斛 hú, which is a large volume; the 斗 dǒu, which at the time of the Hàn dynasty was one tenth the volume of the hú; the 升 shēng, which is one tenth the volume of the dǒu; and the 合 gě, which is one tenth the volume of shēng. In the Hàn dynasty, a 龠 yuè was a unit that was used and equated to half a gě, though smaller modern units are the 勺 sháo, which is one tenth of a gě, and the 撮 cuō, which is one tenth of a sháo. The 石 dàn is a unit that could be thought of as being interchangeable with a hú, although from the time of its common use onwards, from the time of the Sòng dynasty, which was founded in the year 960 CE, a hú has since equated to merely five dǒu, while the shí taken its place in signifying ten dǒu.

The modern shēng is one metric litre. Throughout the five centries prior the common era, according to any one of five famous large vessels known to have existed during that period, the Chinese litre of that time can now be calculated to equate to precisely either 182.1, 190, 196, 194 or 202.1 metric millilitres. Leaving minor discrepancies aside, that probably would have continued to some extent over the subsequent empires, the Chinese shēng has over the course of time, from 221 BCE until 220 CE been equal to about 200 millilitres, from 220 CE until 420 CE to 204.5 millilitres, until 586 CE to 300 millilitres, from then until 605 CE increasing to 600 millilitres, from 605 CE until 619 CE back down to 200 millilitres, and then from 618 CE until 960 CE equal to 200 millilitres if a "little shēng" and equal to 600 millilitres if a "big shēng" of that time, then from 960 CE until 1271 CE to 670 millilitres, from 1271 CE until 1368 CE to 950 millilitres, and since 1368 CE to is modern size of 1000 millilitres. It would hence appear the real volume of the units of volume used in China have quite steadily increased to five fold of their original size over the last two thousand five hundred years.

Dates (ziziphus jujuba) are commonly used in traditional formulas, the dose of which is often listed in recipes as a number of pieces rather than as a weight value. Nowadays, there are 700 varieties of red dates6, from those weighing a couple of grams, to those ten times larger, the size of a chicken eggs. It is ironic that the herb which we literally call 'big date' in Chinese would probably have to be on the smaller side of this scale of different sized dates, lest it be used as a substantially greater quantity than the other herbs it is traditional combined in formulas with. Supposing the same quantity of dates were used as the quantity of all of cinnamon, peony root and ginger in the famous cinnamon twig decoction of the Treatise on Cold Damage, those dates would weigh either 3.45 grams or 3.9 grams, depending on which of the two Han dynasty relic weight standards the practitioners of the day were happened to be using. Indeed, modern practitioners tend to suggest that the dates used in such formulas were intended to be around this weight4, and this may also be informed by continuous use of an particular variety of date that has not changed in size over the enduring period. While the larger red date tends to be sweeter, and thus is used in cooking, a smaller variety known as the chicken heart date is richer in amino acids, organic acids and flavanoids, and is thus considered a superior medicinal product6.


  1. E-Clinic (2018) How long can Chinese medicinal herbs be stored for? Do dry Chinese herbs also have a best before date?, accessed 11 August 2019, <>
  2. “Converting decocted formulas in powdered formulas” (2013) How to convert Chinese raw herb decoction dosage into powdered formula dosage, accessed 11 August 2019, <>
  3. Liú, B. (2016) 5 of 6 Chinese herb granule enterprises hit the market, and one multiplies its net profit eighty-five fold in twelve years, accessed 11 August 2019, <>
  4. Dài, Z.N., Wáng, Z.X., Zhèng, Q.X., Cài, M.L. (2016) How to convert the liăng unit from the Shāng Hán Lùn to the modern day gram, Journal of Chinese Medicine 27(1), accessed 12 August 2019, <>
  5. Zhāng, Z.J. (n.d.) The Taiwanese caddy and the Chinese caddy, accessed 12 August 2019, <>
  6. Xiè, Y.A. (2017) What is the difference between a red date and a chicken-heart date? A professional teaches you how to select, accessed 7 July 2020, <>

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