There are 28.35 g in an ounce. That is the answer: 1 avoirdupois ounce equals 28.3495 grams, usually rounded to 28.35 g, and it is the conversion you will use more than any other when a recipe gives weights in ounces and your scale reads grams. If a recipe calls for 4 ounces of chocolate, weigh 113 grams. If it calls for 8 ounces of flour, weigh 227 grams. This page gives you the table, real baking examples, and the difference between an avoirdupois ounce and a troy ounce, because mixing those two up will leave you short by 10 percent.
The conversion table
| Ounces | Grams | Pounds | Kilograms |
|---|---|---|---|
| 1/4 oz | 7.09 g | 0.016 lb | 0.007 kg |
| 1/2 oz | 14.17 g | 0.031 lb | 0.014 kg |
| 1 oz | 28.35 g | 0.063 lb | 0.028 kg |
| 2 oz | 56.70 g | 0.125 lb | 0.057 kg |
| 3 oz | 85.05 g | 0.188 lb | 0.085 kg |
| 4 oz | 113.40 g | 0.25 lb | 0.113 kg |
| 6 oz | 170.10 g | 0.375 lb | 0.170 kg |
| 8 oz | 226.80 g | 0.5 lb | 0.227 kg |
| 12 oz | 340.19 g | 0.75 lb | 0.340 kg |
| 16 oz | 453.59 g | 1 lb | 0.454 kg |
The gram figures are rounded to two decimal places. An ounce is defined as exactly 28.349523125 grams, so the table is exact to the rounding shown.
Worked example 1: chocolate for a cake
A cake recipe calls for 4 ounces of dark chocolate, and your scale reads grams. Four ounces times 28.35 is 113.4 grams, so weigh 113 grams. If the recipe calls for 8 ounces, that is 226.8 grams, or 227 grams, which is also half a pound. The conversion is simple, but the usual mistake is to round too early: if you round 28.35 to 28 and multiply by 8, you get 224 grams, which is 3 grams short — a small error, but in a chocolate cake it can make the difference between a rich crumb and a dry one. Multiply by 28.35, then round the answer, not the conversion factor.
Worked example 2: a small amount of yeast
A bread recipe calls for 1/4 ounce of fresh yeast, and your scale reads grams. A quarter of an ounce is 7.09 grams, so weigh 7 grams. Fresh yeast is sold in small blocks, and a quarter ounce is a common amount for a single loaf. If you are using dried yeast instead, the conversion is different: dried yeast is about three times as strong as fresh yeast by weight, so a quarter ounce of fresh yeast is roughly 2.4 grams of dried yeast, which is about 3/4 of a teaspoon. That is a separate conversion, and it is the one that matters more than the ounce-to-gram maths, because the wrong yeast will ruin the bread.
Worked example 3: a recipe written in ounces only
An old recipe calls for 12 ounces of flour, 8 ounces of sugar, and 4 ounces of butter, and you want to weigh them in grams. Twelve ounces is 340 grams, 8 ounces is 227 grams, and 4 ounces is 113 grams. Those are the numbers to remember: 4 ounces is 113 grams, 8 ounces is 227 grams, and 12 ounces is 340 grams. If you know those three, you can convert most recipes in your head, because recipes are usually written in multiples of 4 ounces. And if you see a recipe that calls for 16 ounces, that is 454 grams, which is a pound, and the conversion is a round number.
Method and source
An avoirdupois ounce is defined as exactly 28.349523125 grams, by international agreement. The avoirdupois system is the one used for food and for most everyday weights in the United States and Britain: 16 ounces make a pound, and a pound is 453.59237 grams. The troy ounce is different: it is 31.1035 grams, and it is used only for precious metals, so you will never meet it in a recipe, but it is the reason some people quote 31 grams for an ounce. If a recipe says "ounce" without any other word, it means an avoirdupois ounce, and 28.35 grams is the figure to use. A fluid ounce is a different thing entirely — it measures volume, not weight — and a fluid ounce of water weighs about an ounce, but a fluid ounce of honey weighs about 1.4 ounces.
Practical guidance
Buy a kitchen scale that reads grams, and use it for every recipe that gives a weight. Weighing is more accurate than measuring by volume, because a cup of flour can weigh anywhere from 120 to 142 grams depending on how you scoop it, while 120 grams is always 120 grams. When you convert ounces to grams, multiply by 28.35 and round the answer to the nearest gram — do not round the conversion factor first. Remember the anchor numbers: 1 ounce is 28 grams, 4 ounces is 113 grams, 8 ounces is 227 grams, and 16 ounces is 454 grams. And if a recipe gives a weight in ounces and a volume in cups for the same ingredient, trust the weight, because it is the more precise figure.
Frequently asked questions
How many grams are in 1 ounce?
There are 28.35 g in 1 avoirdupois ounce. That is the standard conversion for food and cooking. A troy ounce, used for precious metals, is 31.1 g, but you will never meet one in a recipe.
How many grams are in 4 ounces?
There are 113.4 g in 4 ounces. Four ounces is a quarter of a pound, and it is a common amount for chocolate, butter, and cheese in baking. Round it to 113 g on a kitchen scale.
How many grams are in 8 ounces?
There are 226.8 g in 8 ounces. Eight ounces is half a pound, and it is a common amount for flour, sugar, and cream cheese. Round it to 227 g on a kitchen scale.
How many ounces are in 100 grams?
There are about 3.53 ounces in 100 grams. One hundred grams divided by 28.35 is 3.527, which is a useful figure when a European recipe gives a weight in grams and your scale reads ounces.
Is an ounce the same as a fluid ounce?
No. An ounce measures weight, and a fluid ounce measures volume. A fluid ounce of water weighs about an ounce, which is where the confusion comes from, but a fluid ounce of honey weighs about 1.4 ounces, and a fluid ounce of oil weighs about 0.9 ounces. Never swap them.
What is a troy ounce?
A troy ounce is 31.1035 grams, and it is used only for precious metals such as gold and silver. It is not used for food, and if a recipe says "ounce", it means an avoirdupois ounce of 28.35 grams.