How Many Grams Are in an Ounce?
Quick answer: There are 28.3495 grams in one ounce. That figure is for the avoirdupois ounce, the ounce used for food, body weight, and everyday weighing in the United States and the United Kingdom. For quick estimates, 28 grams is close enough, but for baking and precise work, use 28.35 grams.
Exact Conversion: Grams in an Ounce
One ounce is defined as 28.349523125 grams, which is normally rounded to 28.3495 grams. That definition lets you convert in both directions: multiply ounces by 28.3495 to get grams, and divide grams by 28.3495 to get ounces.
| Ounces | Grams |
|---|---|
| 0.5 ounce | 14.17 grams |
| 1 ounce | 28.35 grams |
| 2 ounces | 56.70 grams |
| 4 ounces | 113.40 grams |
| 8 ounces | 226.80 grams |
| 16 ounces | 453.59 grams |
Notice that 16 ounces make one pound, and 16 times 28.3495 equals 453.59 grams, which is the gram weight of a pound. You can check any amount with the grams to ounces converter, or work the other way with the kilograms to pounds converter for larger amounts.
What Does One Ounce Look Like in Real Life?
One ounce is a small amount, about the weight of a slice of bread, a small packet of crisps, or five sheets of standard paper. A single serving of cheese, about the size of a matchbox, often weighs close to one ounce. In cooking, one ounce of butter is two tablespoons, and one ounce of chocolate is a small square from a bar.
Four ounces is about 113 grams, a single serving of meat or fish for many people, and eight ounces is half a pound, about 227 grams.
How to Convert Ounces to Grams Step by Step
First, check that you are using avoirdupois ounces, the normal ounce for food and everyday items. Then multiply the number of ounces by 28.3495. For example, 3 ounces times 28.3495 equals 85.05 grams. For 0.5 ounces, half of 28.3495 gives 14.17 grams.
To convert grams to ounces, do the reverse: divide grams by 28.3495. For example, 1,000 grams divided by 28.3495 equals 35.27 ounces. For 50 grams, the result is 1.76 ounces. Rounding to two decimal places is enough for cooking, while one decimal place is enough for a rough estimate.
When a recipe gives ounces in fractions, convert the fraction first. Three-quarters of an ounce is 0.75 times 28.3495, which is 21.26 grams. One-quarter of an ounce is 7.09 grams. Writing the gram amount next to the ounce amount in a recipe saves you from doing the same sum again.
Common Uses of Ounces and Grams
Ounces are still common in recipes, nutrition labels, and packaging in the United States, while grams are standard in most of the rest of the world. A recipe might call for four ounces of butter, eight ounces of chocolate, or sixteen ounces of flour, and a cook with a gram scale needs to convert each amount.
Ounces are also used for portion sizes, such as a three-ounce serving of meat or a six-ounce serving of yoghurt. In those cases, converting to grams helps you compare products from different countries, because a label in grams and a label in ounces can describe the same portion in different units.
Common Mistakes With Ounces and Grams
One mistake is confusing fluid ounces with weight ounces. A fluid ounce measures volume, not weight, and one fluid ounce of water weighs about 28.35 grams, but one fluid ounce of oil or honey weighs a different amount. Recipes that use fluid ounces for liquids should not be converted as if they were weight ounces for dry ingredients.
Another mistake is confusing the avoirdupois ounce with the troy ounce, used for precious metals. A troy ounce is 31.10 grams, heavier than the normal ounce. Unless you are dealing with gold or silver, you will be using the avoirdupois ounce of 28.3495 grams.
People also round too early. Using 28 grams instead of 28.3495 is fine for one ounce, but for 16 ounces the error grows to about 5.6 grams. Keep the full figure during the calculation and round only at the end.
Frequently Asked Questions
How many grams are in one ounce?
There are 28.3495 grams in one avoirdupois ounce, normally rounded to 28.35 grams.
How many grams are in half an ounce?
Half an ounce is 14.17 grams, from 0.5 times 28.3495.
How many ounces is 100 grams?
One hundred grams is 3.53 ounces, from 100 divided by 28.3495.
Is a fluid ounce the same as an ounce?
No. A fluid ounce measures volume, while an ounce measures weight. They match only for water, by definition.
What is the difference between an ounce and a troy ounce?
A normal ounce is 28.3495 grams, while a troy ounce, used for precious metals, is 31.10 grams.