How Much Does an Ounce Weigh? Quick Answer + Conversion Tables
One ounce (avoirdupois) weighs 28.35 grams, or 1/16 of a pound. A troy ounce — used for precious metals — is heavier, at 31.10 grams. That's the short answer. Below are the conversion tables, the difference between weight ounces and fluid ounces, and the quick reference for cooking, shipping, and everyday measurement.
Quick Reference
| Unit | Equals |
|---|---|
| 1 ounce (avoirdupois) | 28.35 grams |
| 1 ounce (avoirdupois) | 1/16 pound |
| 1 troy ounce | 31.10 grams |
| 1 fluid ounce (US) | 29.57 milliliters (volume, not weight) |
| 1 pound | 16 ounces = 453.59 grams |
| 1 kilogram | 35.27 ounces |
Ounces to Grams
Multiply ounces by 28.35 to get grams.
| Ounces | Grams |
|---|---|
| 0.5 | 14.17 |
| 1 | 28.35 |
| 2 | 56.70 |
| 4 | 113.40 |
| 5 | 141.75 |
| 8 | 226.80 |
| 10 | 283.50 |
| 16 (= 1 lb) | 453.59 |
Ounces to Pounds
Divide ounces by 16 to get pounds.
| Ounces | Pounds |
|---|---|
| 1 | 0.0625 |
| 2 | 0.125 |
| 4 | 0.25 |
| 8 | 0.5 |
| 12 | 0.75 |
| 16 | 1 |
| 32 | 2 |
Avoirdupois vs Troy Ounce
There are two ounces in common use, and they are not the same weight:
- Avoirdupois ounce (28.35 g) — the everyday ounce. Food, shipping, body weight, most consumer goods.
- Troy ounce (31.10 g) — used only for precious metals (gold, silver, platinum) and gunpowder. About 10% heavier than the regular ounce.
If someone says "an ounce of gold weighs more than an ounce of feathers," they are technically correct — the gold is measured in troy ounces, and a troy ounce is heavier than an avoirdupois ounce. When you buy an ounce of gold and an ounce of flour, you are buying different weights.
Ounce vs Fluid Ounce
This is the most common point of confusion. They measure different things.
- Ounce (oz) measures weight. 1 oz = 28.35 grams.
- Fluid ounce (fl oz) measures volume. 1 fl oz = 29.57 milliliters (US).
An 8 oz cup of flour does not weigh the same as 8 fl oz of water. Water is roughly the same in both — 8 fl oz of water weighs about 8.3 oz — but flour is far less dense, so 8 fl oz of flour weighs about 4.5 oz. This is why baking recipes that specify ounces by weight produce more consistent results than recipes that specify volume.
Common Uses
Cooking and baking
Most US recipes use volume measurements (cups, tablespoons), but professional and serious home baking uses weight ounces for consistency. A kitchen scale that reads in ounces and grams is the cheapest accuracy upgrade in a kitchen.
Shipping
USPS, UPS, and FedEx all price packages by weight in ounces (up to 16 oz, then in pounds). Knowing the weight in ounces before you arrive at the counter avoids billing surprises.
Precious metals
Gold, silver, platinum, and palladium are sold in troy ounces, not avoirdupois. If a coin advertises "1 oz silver," it weighs 31.10 grams, not 28.35.
Body weight (international)
The US measures body weight in pounds and ounces; most of the world uses kilograms and grams. A newborn announced as "7 pounds 4 ounces" weighs about 3.29 kg.
FAQ
How much does an ounce weigh in grams?
One avoirdupois ounce weighs 28.35 grams. One troy ounce weighs 31.10 grams.
How many ounces are in a pound?
16 ounces in a pound (avoirdupois). 12 troy ounces in a troy pound, but the troy pound is rarely used today.
Is a fluid ounce the same as an ounce?
No. An ounce measures weight (28.35 grams). A fluid ounce measures volume (29.57 milliliters). They happen to be close for water but very different for everything else.
Why is a troy ounce different from a regular ounce?
The troy ounce comes from a medieval system used for precious metals and survived because the bullion trade kept using it. It's about 10% heavier than the regular avoirdupois ounce.
What does "oz" stand for?
The abbreviation "oz" comes from the Italian word onza, the historical ancestor of the modern ounce. It is not an abbreviation of any English word.
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