Gold Weight Units Explained: Grams, Troy Ounces, Tola, Tael, Baht
Gold is weighed in more units than almost any other consumer product, and mixing them up is an expensive mistake. A troy ounce is not an ordinary ounce. A tola is not a gram. A tael in one market is not quite the same as a tael in another. This guide defines each unit, gives you the conversions, and shows the two traps that cause most unit errors.
The core conversions
| Unit | In grams | Notes |
|---|---|---|
| 1 gram (g) | 1 | Metric standard for jewellery in most markets |
| 1 troy ounce (oz t) | 31.1034768 g | Standard for precious metals worldwide |
| 1 avoirdupois ounce (oz) | 28.3495231 g | Ordinary ounce — NOT used for gold pricing |
| 1 tola | 11.6638 g | Traditional in India, Pakistan, Bangladesh, Nepal |
| 1 tael (Singapore/China, liang) | 37.7994 g | Traditional Chinese unit; local variants exist |
| 1 baht (Thai) | 15.244 g | Thai gold weight unit (1 baht = 15.244 g) |
| 1 kilogram (kg) | 1,000 g | Bullion and wholesale |
The single most important line in that table is the troy ounce: 31.1034768 grams. Every per-ounce gold price you see is per troy ounce unless it explicitly says otherwise.
Trap 1: Troy ounce vs ordinary ounce
A troy ounce is about 10% heavier than an avoirdupois (ordinary) ounce: 31.1035 g versus 28.3495 g. If you divide a per-troy-ounce price by 28.35 instead of 31.1035, you overstate the per-gram price by about 9.7%. On a $3,110.35 per-ounce example, the correct per-gram price is $100.00; the wrong divisor gives $109.71 per gram. That error then flows into every item you value.
Always ask: “Is this price per troy ounce or per ordinary ounce?” For gold, the answer is almost always troy — but “almost always” is not a check. Confirm the unit before you calculate, especially on a price quoted by a general retailer rather than a bullion dealer.
Trap 2: Tola, tael, and local variants
A tola is standardised at 11.6638 grams in South Asia, so 1 tola of 24K gold at the example price of $100 per gram is $1,166.38 in metal value. That conversion is reliable — but confirm whether a local quote is for a tola of fine gold or a tola of a particular karat, because a tola of 22K gold is not a tola of pure gold.
A tael is less standardised. The Singapore/Chinese tael (liang) used in many gold shops is 37.7994 grams, so 1 tael of 24K at the example price is $3,779.94. Other markets have used slightly different tael weights historically. If you are buying in a shop that quotes per tael, ask for the gram weight in writing before you pay. A 1-gram difference on a tael is about $100 at the example price — not a rounding error.
Thai baht weight is another local unit to confirm in writing: 1 baht of gold weight is 15.244 grams. Thai gold is also commonly 96.5% pure (23.16K equivalent), not 99.9%, so a baht price and a 24K price are not directly comparable without a purity conversion as well.
Worked conversions
EXAMPLE ONLY — not today’s price, using $100 per gram for 24K gold.
- 50 grams in troy ounces: 50 ÷ 31.1034768 = 1.6075 oz t. Metal value: $5,000.
- 2 troy ounces in grams: 2 × 31.1034768 = 62.20695 g. Metal value: $6,220.70.
- 3 tola in grams: 3 × 11.6638 = 34.9914 g. At 22K (0.9167 nominal), metal value is 34.9914 × 0.9167 × $100 = $3,207.66 in the example.
- 1 tael (37.7994 g) of 24K: $3,779.94 in the example.
Use the Gram–Troy Ounce Converter for the arithmetic, but check its unit labels before trusting its output. A converter that silently uses avoirdupois ounces will be consistently wrong by about 10%, and consistency can look like correctness until you cross-check it.
How to avoid unit errors when buying or selling
Write the unit next to every weight and price in your own notes: “20 g, 18K, $100/g example” is checkable; “20, 18K, $100” is not. When a dealer quotes per tola, per tael, or per ounce, ask them to also state grams. When a price is quoted per kilogram, divide by 1,000 for per-gram — and confirm the kilogram is metric, not a local “kilo” variant. Photograph any shop ticket that states weight, so a later dispute has evidence.
Frequently asked questions
How many grams are in a troy ounce? 31.1034768 grams, exactly for conversion purposes. Round to 31.10 g for quick mental maths, but use the full figure for a sale calculation.
Is a tola the same everywhere? The standard South Asian tola is 11.6638 g. Confirm it in writing for any specific shop or market, especially for older or cross-border quotes.
Why is gold not priced per ordinary ounce? Because precious metals have used the troy system for centuries, and the market has never switched. The two systems coexist, which is exactly why the trap exists.
What unit should I use in a calculator? Grams, if the calculator accepts them, because gram is unambiguous. Convert to troy ounces only for comparing with a per-ounce price, and state which ounce you used.
Estimates only. A calculator result is metal value, not a dealer payout or a retail price. This article is general information, not personal financial advice.
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