Quick answer
What this calculator tells you
A troy ounce is about 10% heavier than the regular ounce on food packaging. Mixing the two is the most common mistake in precious metal math. Enter either unit and get the other, plus grams and pennyweights.
Formula
Troy Ounce to Regular Ounce Converter formula
Regular ounces = troy ounces x 1.09714. One troy ounce = 31.1035 g; one regular ounce = 28.3495 g.
Use cases
When to use it
- Sanity-check a bullion listing that only says "ounce".
- Convert a postal-scale reading in regular ounces into troy ounces.
- Explain to a buyer or seller why the two ounce figures differ.
Limits
What to check before relying on the number
- Spot prices always use troy ounces — never regular ounces.
- Postal and kitchen scales read regular ounces unless labeled ozt.
- A "1 oz" silver round is one TROY ounce (31.1 g), not 28.35 g.
FAQ
Common questions
Is a troy ounce heavier than a regular ounce?
Yes. A troy ounce is 31.1035 grams, a regular avoirdupois ounce is 28.3495 grams — the troy ounce is about 9.7% heavier.
Why do precious metals use troy ounces?
The troy system survives from medieval bullion markets and remains the global standard for quoting gold, silver, and platinum prices.
Is a 1 oz gold coin a troy ounce?
Yes. Bullion coins like the American Gold Eagle contain one full troy ounce (31.1035 g) of metal, not one regular ounce.