Convert Tahil/Tael to troy ounces

One-sixteenth of a catty

The tahil sits in the middle of the catty ladder: sixteen tahil make one catty, and one hundred catty make one pikul. Hong Kong law fixes the catty at 604.78982 grams, so the tahil is 37.799 g — a statutory figure, not an approximation, which is unusual for a unit this old.

The sixteen-part division is why traditional Chinese steelyard balances (dàchèng) are marked in sixteenths rather than tenths, and why the idiom about two things being "half a catty, eight tahil" means they are equal. The arithmetic of the unit is built into the language that uses it.

Gold, medicine and the trades that kept it

Hong Kong's gold market quotes per tael, and the Chinese Gold and Silver Exchange Society contract is denominated in taels rather than troy ounces. One tael is about 1.2153 troy ounces, so a tael price and a spot price per troy ounce are not directly comparable — a frequent source of confusion for buyers reading Hong Kong quotes against London ones.

Traditional Chinese medicine dispensaries in Hong Kong, Malaysia and Singapore weigh herbs in tahil and qian (mace, one-tenth of a tahil), and prescriptions are written that way. Loose-leaf tea, dried seafood and birds' nest are also sold by tahil in traditional shops across the region.

Regional values are not identical

Hong Kong's 37.799 g and the mainland Chinese market liang of exactly 50 g are different units with the same Chinese name. The mainland redefinition made ten liang to a jin of 500 g, abandoning the sixteen-part division entirely, so a mainland recipe and a Hong Kong prescription using 兩 mean quantities that differ by a third.

Taiwan kept the older ratio: the Taiwanese tael is 37.5 g, one-sixteenth of a 600 g jin inherited from Japanese-era standards. Malaysian and Singaporean usage generally follows the Hong Kong figure. Three neighbouring markets, three values, one word.

Converting a tahil figure safely

Establish the jurisdiction before the arithmetic. "Two tahil of ginseng" is 75.6 g in Hong Kong, 75 g in Taipei and 100 g in Shanghai, and none of those is a rounding error — they are different systems.

For bullion, convert to grams first and to troy ounces only at the end, quoting the factor. For medicine, prefer the practitioner's own regional standard over a generic conversion: dosage is the one context where guessing the variant has consequences beyond accounting.

Reading a tael figure safely

Because the tael exists in a Hong Kong statutory version, a mainland market version and several historical port versions, the safest practice is to record the jurisdiction alongside every converted figure. A Hong Kong gold invoice, a Singapore herb receipt and a mainland recipe using the same character are not describing the same mass.

For gold specifically, the useful cross-check is the price. Hong Kong tael quotes and London troy-ounce quotes should differ by roughly the 1.2153 ratio between the units once purity is aligned; if a converted figure implies a much wider gap, the wrong tael or the wrong fineness is in play. Doing that check before settlement is considerably cheaper than doing it afterwards.

Common mistakes to avoid

• Mainland Chinese liang is exactly 50 g; Hong Kong tahil is 37.799 g and Taiwanese is 37.5 g — the same character, three values.
• One tahil is about 1.2153 troy ounces, so Hong Kong gold quotes cannot be compared directly with per-troy-ounce spot prices.
• Sixteen tahil make a catty in the traditional ladder, but only ten liang make a mainland jin — the division changed, not just the size.

Questions people ask about the Tahil/Tael

How many grams is one tahil?

In Hong Kong, exactly 37.799 g by statute (one-sixteenth of a 604.78982 g catty). Taiwan uses 37.5 g and mainland China uses a 50 g liang.

Is a tahil the same as a tael?

Yes — tahil is the Malay form, tael the English trade form and liang the Chinese name. The value still depends on which market you are in.

How many troy ounces is a tael of gold?

About 1.2153 troy ounces for the Hong Kong tael. A tael price is therefore roughly 21.5% higher than the equivalent per-troy-ounce price.