Troy Ounce to Grams Converter — Live Gold Money Value
A troy ounce is the international standard unit for precious metals: 1 troy ounce (oz t) = 31.1034768 grams (commonly rounded to 31.1035 g). It is heavier than the avoirdupois ounce used for groceries (28.3495 g) — confusing two ounces by 10% leads to large valuation errors when buying or selling gold.
This converter takes a troy-ounce input and returns the exact gram weight, the equivalent in pennyweight (1 troy oz = 20 dwt), grains (1 troy oz = 480 grains), tola (1 troy oz = 2.6667 tola), and the money value at the live international XAU/USD spot rate.
When to use this calculator
- International bullion trade — COMEX, LBMA, ICE Futures and major refiners (PAMP, Valcambi, Argor-Heraeus) all quote troy ounces.
- Coin investment — Krugerrand, Maple Leaf, American Eagle and Vienna Philharmonic are 1 troy oz (and fractional 1/2, 1/4, 1/10 oz coins).
- ETF/futures correlation — gold ETFs (GLD, IAU, etc.) hold troy-ounce inventories; checking parity requires converting share holdings to gram-equivalent.
- Refiner intake — most international refiners accept gross weight in grams but pay out in troy ounces of pure gold recovered.
The Troy Weight System in Precious-Metal Markets
The troy ounce descends from the weight system used at the medieval Troyes fair in the Champagne region of France, where merchants from across Europe traded precious metals on standardised balances. It was formalised in English law under Henry VIII and adopted as the US legal precious-metal standard by the Mint Act of 1828. Today, the LBMA London Gold Price (fixed twice daily), COMEX futures contracts, and OTC interbank gold swaps are all denominated in troy ounces.
The troy ounce (31.1035 g) is intentionally heavier than the avoirdupois ounce (28.3495 g) used for everyday goods. This 10% mass difference means confusing the two units produces a large, identifiable error — an important safeguard in a market where misquotes of 1% have material financial consequences. When buying or selling gold, always verify whether an "ounce" quote specifies troy.
For conversions to South Asian units, the troy ounce to tola calculator handles the tola/masha/ratti equivalent directly. For institutional-scale gold, the kg to troy ounce converter provides the 32.1507 oz/kg ratio used in kilobar trading.
How the conversion works
Grams = Troy ounces × 31.1034768. Money value = Troy ounces × live XAU/USD spot price (the spot rate is already troy-ounce denominated, so this is the simplest of the conversions). For local currency: Money = (Troy oz × spot $) × FX rate.
Step-by-step calculation
Example: 5 troy oz of 22K gold
- 1
Convert troy oz to grams
grams = troy oz × 31.1035
5 × 31.1035 = 155.518 g
- 2
Convert grams to tola
tola = grams ÷ 11.664
155.518 ÷ 11.664 = 13.333 tola
- 3
Calculate pure gold at 22K
pure (g) = grams × (22 ÷ 24)
155.518 × 0.9167 = 142.558 g pure
- 4
Calculate alloy mass
alloy = gross − pure
155.518 − 142.558 = 12.960 g alloy
Sample conversions
| Input | Result |
|---|---|
| 1 troy ounce | 31.1035 g (= 20 dwt = 480 grains) |
| 1 troy ounce | 2.6667 tola = 32 masha = 256 ratti |
| 5 troy ounces | 155.517 g (= 100 dwt) |
| 10 troy ounces | 311.035 g (= 1 troy pound) |
| 32.1507 troy oz | 1,000 g = 1 kg (typical retail bullion bar) |
Quick Reference — Troy Ounces to Grams
| Troy Oz | Grams |
|---|---|
| 0.1 oz | 3.110 g |
| 0.25 oz | 7.776 g |
| 0.5 oz | 15.552 g |
| 1 oz | 31.103 g |
| 2 oz | 62.207 g |
| 5 oz | 155.517 g |
| 10 oz | 311.035 g |
| 32.151 oz | 1,000 g |
1 troy oz = 31.1034768 g exactly. Troy ounce ≠ avoirdupois ounce (28.3495 g) — a 10% difference.
Frequently asked questions
Why is a troy ounce different from a regular ounce?
The troy ounce (31.1035 g) comes from the medieval Troyes market (France) and was used exclusively for precious metals. The avoirdupois "regular" ounce (28.3495 g) is used for everyday goods. The 10% difference is large enough to cause serious errors — always specify "troy" in any gold or silver transaction.
How many troy ounces in a kilogram of gold?
1 kg = 32.1507 troy ounces (1,000 ÷ 31.1035). A retail kilobar contains slightly more than 32 troy oz, which is why kilobars trade at a small per-ounce premium over equivalent 1-oz coin stacks — you get more gold per handling/refining cost.
Is a 1 oz American Gold Eagle really 1 troy ounce of pure gold?
Yes — it contains exactly 1 troy oz of pure gold. But its gross weight is 33.93 g because it is alloyed at 22K (91.67%) for durability. By contrast, Canadian Maple Leaf and US Buffalo coins are 24K (99.99%) and weigh exactly 31.1035 g gross — pure gold equals gross weight.
How many grams is 1 troy ounce exactly?
31.1034768 grams, commonly rounded to 31.1035 g. This is the internationally recognised value (NIST, ISO) and is what all major exchanges — LBMA, COMEX, Shanghai Gold Exchange — use as the reference for XAU/USD gold price quotations.
What is the symbol for troy ounce and how do I read gold prices?
The troy ounce is abbreviated "oz t" in formal writing or simply "oz" in precious-metal contexts (where "oz" is always understood as troy). Spot price displays show "XAU/USD" where XAU is gold per 1 troy ounce. Multiply by your FX rate to get the local-currency per-troy-oz price.
How many troy ounces is a standard gold bar?
The LBMA Good Delivery bar weighs 350–430 troy oz (10.9–13.4 kg). Retail kilobars are 32.1507 troy oz. Smaller bars are sold in 1 oz, 10 oz, 50 g, 100 g and 250 g sizes. Coin denominations run 1/10 oz, 1/4 oz, 1/2 oz and 1 oz for the most common fractions.
Why does the gold spot price use troy ounces instead of grams?
The troy ounce was the standard precious-metal weight in London (the original gold market) when the international gold price benchmark was established in the early 20th century. The LBMA Gold Price (fixed in London since 1919) has always been per troy ounce, and global markets quote it the same way for consistency.
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