What Is a Troy Ounce? Troy Ounce vs Ounce Explained (2026)

The short answer: a troy ounce is the unit used to weigh gold, silver, platinum and palladium. It equals 31.1035 grams, about 10% more than the ordinary ounce used for food and parcels, which is 28.3495 grams. Whenever you see a price for gold or silver "per ounce", it means per troy ounce.

The difference trips people up all the time: a "1 ounce" gold coin weighs more than an ounce on a kitchen scale, and a "pound" of gold is not 16 ounces. This page explains the troy system, gives the conversions you are likely to need, and shows what a troy ounce of gold is worth at today's price.

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Troy ounce vs ounce

The ordinary ounce is the avoirdupois ounce, the everyday unit in the United States. The troy ounce belongs to a separate, older system kept by the precious metals trade.

A troy ounce is 1.0971 ordinary ounces, so it is about 9.7% heavier. Going the other way, an ordinary ounce is 0.9115 troy ounces.

The pound puzzle

The troy system has an odd twist. Its ounce is heavier than an ordinary ounce, but its pound is lighter, because a troy pound has only 12 ounces:

• A troy pound is 12 × 31.1035 = 373.24 grams.
• An ordinary pound is 16 × 28.3495 = 453.59 grams.

The troy pound is rarely used today; gold and silver are priced by the troy ounce and the kilogram. But if you buy "a pound of silver" by everyday weight, you get 14.58 troy ounces, not 12 or 16.

Troy ounce conversions

The conversion factors come from the National Institute of Standards and Technology (NIST), which gives a troy ounce as 31.10348 grams, a pennyweight as 1.555174 grams and a grain as 64.79891 milligrams.

The rest of the troy system

• Grain. The smallest unit, 64.79891 milligrams. It is the one unit the troy and ordinary systems share: a troy ounce is 480 grains and an ordinary ounce 437.5 grains.
• Pennyweight (dwt). One twentieth of a troy ounce, 1.555 grams. Jewelers and scrap gold buyers often quote prices per pennyweight.
• Troy ounce. 20 pennyweights, or 480 grains.
• Troy pound. 12 troy ounces.

The name is usually traced to Troyes, a market town in France whose medieval trade fairs drew merchants from across Europe, though historians are not certain of the origin.

What a troy ounce of gold is worth today

Gold value by weight, at the price above

Weight	Value
1 gram	$128.64
1 pennyweight (1.555 g)	$200.05
1 troy ounce	$4,001.10
1 pound (453.6 g)	$58,349.28
1 kilogram	$128,638.26

The table gives the value of pure gold in each unit at the current price, without a dealer's premium. The chart shows how the price per troy ounce has moved over time; the gold bullion price chart has the full history, and the silver price per ounce page does the same for silver.

Where troy ounces trip people up

• Weighing a coin at home. A one ounce gold or silver coin weighs about 1.1 ounces on a kitchen or postal scale. That is not a sign of a fake, just the difference between the two ounces.
• Coins that are not pure. A 22 karat coin such as the American Gold Eagle contains one troy ounce of gold, but it weighs more than that because of the copper and silver mixed in to harden it. Its price is based on the gold content.
• Jewelry and scrap. Jewelry is weighed in grams or pennyweights, and it is rarely pure. A 14 karat chain is about 58% gold, so its gold content is well below its weight.
• "Ounce" prices in ads. A price per ounce from a dealer means per troy ounce. If a listing gives a weight in ordinary ounces or pounds, convert it before you compare.
• Bar sizes. A 1 kilogram bar is 32.15 troy ounces, not 35.27 (which is the number of ordinary ounces in a kilogram). Our guide to how much a gold bar weighs lists every common size.

Why precious metals still use troy ounces

Gold and silver were weighed in troy units long before the metric system existed, and the trade never changed. Prices on the world's main markets, from the London benchmark prices to COMEX futures in New York, are quoted per troy ounce, and refiners stamp bars with their weight in troy ounces or grams. Keeping one unit across every market means a price in New York, London or Zurich can be compared directly.

Buying gold and silver by the troy ounce

If you are buying gold or silver for your retirement savings, the quote you are given should be clear about the troy ounces of metal you get and the price per ounce. Augusta Precious Metals, our first-ranked company, explains how a gold or silver IRA works before any sale and publishes its custodian and depository. Its minimum is $50,000. Our Augusta Precious Metals review covers it in full, and our ranking compares the companies we cover.

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FAQ

How many grams are in a troy ounce?

31.1035 grams (31.10348 grams to NIST's precision).

Is a troy ounce bigger than a regular ounce?

Yes. A troy ounce is 31.1035 grams and a regular ounce 28.3495 grams, so a troy ounce is about 9.7% heavier.

How many troy ounces are in a pound?

A troy pound has 12 troy ounces. An ordinary pound, the one on a bathroom scale, holds 14.58 troy ounces.

How many troy ounces are in a kilogram?

32.1507 troy ounces.

Why is gold measured in troy ounces?

Because the precious metals trade has used the troy system for centuries, and the world's gold and silver markets all quote prices per troy ounce.

Is the gold price per ounce per troy ounce?

Yes. Any quoted gold, silver, platinum or palladium price per ounce is per troy ounce.

What is a pennyweight?

One twentieth of a troy ounce, 1.555 grams. It is common in the jewelry and scrap gold trades.

Does a 1 ounce gold coin weigh exactly one ounce?

It contains one troy ounce of gold. On a kitchen scale it reads about 1.1 ounces, and a 22 karat coin such as the American Gold Eagle weighs more again because of its alloy.

Sources

• NIST Special Publication 811, Appendix B.9: factors for units listed by kind of quantity (troy ounce 31.10348 g, pennyweight 1.555174 g, troy pound 0.3732417 kg, grain 64.79891 mg, avoirdupois pound 0.4535924 kg), read November 11, 2026
• Gold prices: COMEX gold futures (GC=F) daily closes from Yahoo Finance and the gold spot price from api.gold-api.com, refreshed automatically. Unit values are calculated from the price per troy ounce.

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