Gold is quoted per troy ounce in London and New York, but most of the world buys and sells it by the gram or the kilo. Enter the current price per ounce below, then a weight or a dollar amount, and the converter returns the exact value using the troy system (1 troy ounce = 31.1035 g) — the convention the professional gold market actually uses.
The gold market quotes in troy ounces, not the everyday ounce used for food. One troy ounce is 31.1035 grams, slightly heavier than the 28.35 g avoirdupois ounce. That is why "gold price per ounce" and "gold price per gram" never line up with a simple 28.35 multiplication, and why a converter built on the wrong ounce is off by roughly nine percent.
Divide the ounce price by 31.1035 to get the price per gram, then multiply by 1,000 for the kilo price. With gold at $4,180 per ounce, one gram is worth about $134.39 and one kilo about $134,390 — a number worth checking before you agree to any large physical purchase or sale.
The troy system comes from the medieval fair at Troyes and survived because precious metals never switched to the imperial ounce. Jewellers, refiners, mints and central banks all settle in troy ounces, and every XAUUSD contract is sized in them. If a dealer quotes you a price "per ounce" and then weighs your metal on a kitchen scale in imperial ounces, the difference between 31.10 g and 28.35 g is money leaving your pocket. Ask which ounce is meant, every time.
Pure gold is 24 karat, marked 999 or 999.9 fine. Everything else is an alloy: 22K is 91.6% gold and 18K is 75%. A gram of 18K jewellery therefore contains only 0.75 g of gold, so its melt value is a quarter below the 24K price shown above, before any dealer margin. That gap explains why the buy-back price for a gold chain is always lower than the spot price per gram that people see online.
In mainland China gold is commonly quoted per tael (两), defined as 50 grams. Hong Kong uses a different tael of 37.429 g, and India uses the tola of 11.6638 g. Dubai and much of the Gulf quote per gram directly. When you compare a price in Bangkok, Hong Kong or Mumbai with a London spot quote, convert the local unit to grams first — a "cheap" tael price can be expensive once the unit is corrected.
| Unit | In grams | In troy ounces |
|---|---|---|
| 1 gram (g) | 1 | 0.032151 |
| 1 kilogram (kg) | 1,000 | 32.1507 |
| 1 troy ounce (oz t) | 31.1035 | 1 |
| 1 tael (两, mainland) | 50 | 1.60754 |
| 1 tael (Hong Kong) | 37.429 | 1.20337 |
| 1 tola (India) | 11.6638 | 0.375000 |
| 1 avoirdupois ounce | 28.3495 | 0.911458 |
Physical buyers use the gram price to sanity-check a dealer quote: multiply the gram price by the weight on the certificate and compare it with the invoice. Sellers use it to estimate melt value before walking into a shop, which removes most of the room for a lowball offer. Traders use the kilo price to translate an XAUUSD move into the P&L of a 1 kg bar, and to see how a $10 move in the ounce price becomes roughly $0.32 per gram.
Remember that spot is an interbank reference, not a retail price. Coins and small bars carry a premium that can range from a few percent to well over ten for scarce items, and buy-back spreads widen further in small sizes. The converter tells you what the metal is worth, not what a particular shop will pay — but knowing the former is the only reliable defence when negotiating the latter.
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