Troy ounce
1 ozt = 31.1034768 grams = 20 dwt = 480 grains. Gold spot prices use this ounce.
Weight conversion · no market price required
Gold Weight Converter
Convert a gold scale reading into the units used by dealers and bullion specifications. Results show gross weight; use a gold value calculator separately to apply purity and market price.
Reviewed and updated
Convert gold weight
| Unit | Equivalent weight |
|---|---|
| Grams (g) | 31.1034768 |
| Troy ounces (ozt) | 1 |
| Pennyweight (dwt) | 20 |
| Regular ounces (oz) | 1.0971429 |
| Kilograms (kg) | 0.0311035 |
| Grains | 480 |
| Tola (11.6638 g) | 2.6666675 |
| Thai jewellery baht (15.244 g) | 2.040375 |
This converts gross weight only. Purity and price are separate. Thai jewellery baht and bullion baht use different weights; this tool uses the 15.244 g jewellery convention.
Regular ounce
1 ordinary ounce = 28.349523125 grams. It is about 8.85% lighter than a troy ounce.
Regional conventions
This tool uses 11.6638 g per tola and 15.244 g per Thai jewellery baht. Confirm local product specifications before valuing bullion.
How to convert a gold weight
- 1Read the exact unit displayed on your scale or the item’s specification.
- 2Enter a non-negative weight and choose its original unit in the converter.
- 3Read the equivalent weight from the result table; do not apply purity while converting units.
- 4For a metal estimate, take the converted weight to the gold value calculator and select the item’s karat.
To put this into practice, use Gold Value Calculator, check the assumptions with Gold Price per Pennyweight Calculator, and compare the result in Gold Price Per Gram.
Troy ounces versus ordinary ounces
A troy ounce is 31.1034768 grams, while an ordinary avoirdupois ounce is 28.349523125 grams. Both can be abbreviated oz, which makes a bare ounce label ambiguous. Bullion specifications and market gold prices normally use the troy unit. Kitchen and postal scales normally use the ordinary unit, but check the model’s instructions rather than relying on the label alone.
One ordinary ounce is about 0.91146 troy ounces. If you treat an ordinary-ounce scale reading as a troy-ounce reading, you overstate the weight used for pricing by about 9.71%. Converting to grams first is a straightforward way to expose that mismatch. Changing the unit changes the written number, not the physical amount of gold.
Grams, pennyweights and grains
A pennyweight, abbreviated dwt, is one twentieth of a troy ounce: 1.55517384 grams. A grain is one 480th of a troy ounce: 0.06479891 grams. There are 24 grains in a pennyweight. A kilogram contains 1,000 grams. The converter keeps these factors at full precision internally and rounds the displayed equivalents so repeated conversions do not rely on shortened factors.
For example, 10 dwt converts to 15.5517384 grams, and 20 dwt converts to 31.1034768 grams. A 10 gram item is about 6.43015 dwt. These conversions apply to any material; they say nothing about whether the item is 9K, 18K, plated or solid gold. Fineness belongs in a separate purity calculation after the weight is understood.
Tola, Thai baht and fine-gold weight
Regional units require care because published weights can differ between product categories. This tool uses the site’s stated convention of 11.6638 grams per tola. For Thai baht it uses 15.244 grams for jewellery; a bullion bar commonly uses 15.16 grams instead. The Thai weight unit is separate from the THB currency. Use the product’s documented gram weight when it differs from a preset.
Also distinguish gross weight from fine-gold weight. A 10 gram 18K object has 10 grams of alloy and 7.5 grams of fine gold under the nominal karat formula. A coin specification may already state its fine-gold content. Converting that fine weight to another unit does not require multiplying by karat again. Keep the weight basis attached to your notes so an estimate is not reduced twice.
Primary sources and further reading
We use primary or official references for measurement, purity, hallmark, and coin specifications. Market prices remain time-sensitive and are timestamped separately.
- NIST — Precious Metals Conversion Information — Official guidance and conversion factors for troy ounces, grams, pennyweights and grains.
Common questions
How many grams are in one troy ounce of gold?
One troy ounce is exactly 31.1034768 grams. The common rounded figure for a price calculation is 31.1035 grams.
Does gold purity change the weight conversion?
No. One gram remains one gram at any karat. Purity determines the amount of fine gold within that measured weight.
Can this calculate gold value without a price?
It converts weight without a market feed. To estimate money value, you also need a price and the item’s tested purity.
What is the difference between tola and baht?
They are different regional weight units. This converter uses 11.6638 grams per tola and 15.244 grams per Thai jewellery baht.
Open the calculator
Enter weight, purity, currency, and payout percentage in the main tool.