To convert grams to ounces, divide by 28.35 (or multiply by 0.035274). So 100 g is 3.53 oz, 250 g is 8.82 oz and 500 g is 17.64 oz. To go from ounces to grams, multiply by 28.35. Those are avoirdupois ounces, the ones on a kitchen scale. Gold and silver use a heavier troy ounce, covered below.
How many grams are in an ounce? #
One avoirdupois ounce is exactly 28.349523125 g. It’s defined as 1/16 of a pound, and the pound is defined as exactly 0.45359237 kg, the international definition agreed in 1959 and written into UK law in the Weights and Measures Act 1985. Dividing 453.59237 g by 16 gives the ounce.
For almost every everyday purpose, 28.35 g is enough precision. US nutrition labels use an even rounder number: FDA labeling rules say “1 oz in weight means 28 g” (21 CFR 101.9).
The mental shortcut #
Multiply grams by 0.035. It’s about 0.8% low: 200 g becomes 7 oz (exact: 7.05). Or divide by 28, which runs about 1% high. Avoid dividing by 30. It’s popular because it’s easy, but it’s almost 6% off, which is a noticeable difference in baking.
For ounces to grams, multiply by 28, and you’ll be about 1% low. 8 oz becomes 224 g against the exact 226.8.
Grams to ounces chart #
| Grams | Ounces | Grams | Ounces | |
|---|---|---|---|---|
| 1 | 0.035 | 150 | 5.291 | |
| 5 | 0.176 | 200 | 7.055 | |
| 10 | 0.353 | 227 | 8.007 | |
| 20 | 0.705 | 250 | 8.818 | |
| 25 | 0.882 | 300 | 10.582 | |
| 30 | 1.058 | 340 | 11.993 | |
| 50 | 1.764 | 400 | 14.110 | |
| 85 | 2.998 | 454 | 16.014 | |
| 100 | 3.527 | 500 | 17.637 | |
| 113 | 3.986 | 750 | 26.455 | |
| 125 | 4.409 | 1,000 | 35.274 |
Ounces to grams chart #
| Ounces | Grams |
|---|---|
| 1/4 oz | 7.1 |
| 1/2 oz | 14.2 |
| 1 oz | 28.3 |
| 2 oz | 56.7 |
| 3 oz | 85.0 |
| 4 oz (1/4 lb) | 113.4 |
| 5 oz | 141.7 |
| 6 oz | 170.1 |
| 8 oz (1/2 lb) | 226.8 |
| 10 oz | 283.5 |
| 12 oz (3/4 lb) | 340.2 |
| 16 oz (1 lb) | 453.6 |
| 24 oz (1 1/2 lb) | 680.4 |
| 32 oz (2 lb) | 907.2 |
Are ounces and fluid ounces the same? #
No. An ounce measures weight. A fluid ounce measures volume. A kitchen scale in ounce mode reads weight, and a liquid measuring cup reads fluid ounces. They only roughly agree for water: 1 US fluid ounce of water weighs about 1.04 oz.
So if a recipe lists “8 oz chocolate,” it means weight: 226.8 g on a scale. If it lists “8 fl oz milk,” it means volume: 1 cup. When a recipe gives “oz” for a liquid and doesn’t say which, look at how it lists the other ingredients. The distinction gets its own article in fluid ounces vs dry ounces.
What is a troy ounce? #
Gold, silver, platinum and other precious metals are weighed in troy ounces, not the kitchen ounce. A troy ounce is 480 grains, and since a grain is exactly 64.79891 mg, a troy ounce is exactly 31.1034768 g. That’s about 9.7% heavier than an avoirdupois ounce.
When a bullion price is quoted “per ounce,” it means per troy ounce. A 1 oz gold coin contains 31.1 g of gold, not 28.35 g. NIST’s weights and measures guidance says precious metal sales should use troy weight or SI units, and many dealers’ scales read in grams. Gemstones use yet another unit, the metric carat, which is 0.2 g.
Worked examples #
A British recipe calls for 225 g of dark chocolate. 225 ÷ 28.35 = 7.94 oz. An 8 oz bar is close enough, with 1.8 g to spare.
A nutrition guide suggests a 4 oz portion of chicken. 4 × 28.35 = 113.4 g.
A package says 340 g. 340 ÷ 28.35 = 11.99 oz. US packaging prints both, and this one is a 12 oz package.
You’re weighing a letter on a kitchen scale in grams. 1 oz is 28.35 g, 2 oz is 56.7 g, 3 oz is 85 g. Check your postal service’s current rules for which weight steps apply.
Converting grams and ounces on your phone #
Convert Units Calculator converts milligrams, grams and kilograms to ounces and pounds in its Weight category, using the exact 28.349523125 g ounce, and lists every other weight unit underneath as you type. It also has carats. When you’re going from a recipe’s cups to ounces, its Cooking category (version 1.0.5 and later) asks which ingredient first, then converts cups or spoons straight to ounces or grams.
For heavier weights, see kg to lbs. For specific ingredients, the cups to grams conversion chart lists 23 of them, and a cup of butter in grams covers the sticks.
Frequently asked questions #
How many grams are in an ounce? #
One avoirdupois ounce is 28.35 g (exactly 28.349523125 g). A troy ounce, used for precious metals, is 31.10 g.
How many ounces is 100 grams? #
100 g is 3.53 ounces.
Is 1 ounce 30 grams? #
No, it’s 28.35 g. Rounding to 30 g makes each ounce about 6% too heavy. US nutrition labels round to 28 g per ounce, which is much closer.
How many grams is 8 ounces? #
8 oz is 226.8 g, half a pound. Recipes often round it to 225 or 227 g.
How many ounces are in a kilogram? #
A kilogram is 35.27 avoirdupois ounces, or 2 lb 3.27 oz.