How Many Grams in an Ounce?
There are exactly 28.3495 grams in one ounce. This guide covers the formula, worked examples, a quick reference chart, and practical applications.
Last updated: 2025-03-15
The Short Answer
There are 28.3495 grams in one ounce. More precisely, one avoirdupois ounce equals 28.349523125 grams. This is the standard ounce used in the United States, the United Kingdom, and other countries that employ imperial or US customary measurements for everyday weighing. The conversion factor is defined by international agreement and does not change.
The Formula
Converting between ounces and grams requires a single multiplication:
grams = ounces × 28.3495
To convert in the other direction:
ounces = grams / 28.3495
Alternatively, you can multiply grams by 0.035274 to get ounces.
Worked Examples
Example 1: Convert 4 ounces to grams
- Step 1: Multiply ounces by 28.3495.
- Step 2: 4 × 28.3495 = 113.398 grams.
- Result: 4 oz = 113.4 g (rounded to one decimal).
Example 2: Convert 250 grams to ounces
- Step 1: Divide grams by 28.3495.
- Step 2: 250 / 28.3495 = 8.818 ounces.
- Result: 250 g ≈ 8.82 oz.
Example 3: Convert 10 ounces to grams
- Step 1: 10 × 28.3495 = 283.495 grams.
- Result: 10 oz ≈ 283.5 g.
For instant results with full precision, use our weight converter.
Quick Reference Table
| Ounces (oz) | Grams (g) |
|---|---|
| 0.5 | 14.17 |
| 1 | 28.35 |
| 2 | 56.70 |
| 3 | 85.05 |
| 4 | 113.40 |
| 5 | 141.75 |
| 6 | 170.10 |
| 8 | 226.80 |
| 10 | 283.50 |
| 12 | 340.19 |
| 16 (1 lb) | 453.59 |
Avoirdupois Ounce vs Troy Ounce
It is important to know that there are two types of ounce in common use. The avoirdupois ounce (28.3495 g) is the everyday ounce used for food, packages, and body weight. The troy ounce (31.1035 g) is used exclusively for precious metals such as gold, silver, and platinum. When someone quotes the price of gold “per ounce,” they always mean troy ounces. The troy ounce is about 10% heavier than the avoirdupois ounce.
Real-World Applications
Cooking and Baking
Recipes from the US often list ingredients in ounces, while European and Asian recipes use grams. A recipe calling for 6 oz of chocolate means 170 grams. Precise conversions matter especially in baking, where small weight differences affect texture and rise.
Nutrition Labels
US nutrition labels list serving sizes in grams alongside ounces. A “1 oz serving” of chips is 28 grams, which helps you compare across brands that may label differently.
Postal and Shipping
The US Postal Service uses ounces for first-class letter pricing (up to 3.5 oz for letters), while international shipping often requires grams or kilograms. Knowing that each ounce is about 28.35 grams helps you estimate shipping costs accurately.
Science and Lab Work
Scientific work uses grams exclusively. If you are following a procedure written in US units, converting ounce measurements to grams ensures compatibility with metric lab equipment such as precision balances.
Frequently Asked Questions
How many grams are in one ounce?
There are exactly 28.3495 grams in one avoirdupois ounce. This is the standard ounce used for everyday weight measurements in the United States and United Kingdom.
How many grams are in a troy ounce?
A troy ounce, used for precious metals like gold and silver, contains 31.1035 grams. This is about 10% heavier than a standard avoirdupois ounce.
How do I convert ounces to grams without a calculator?
For a quick estimate, multiply the number of ounces by 28. For example, 4 ounces is approximately 4 × 28 = 112 grams. The exact value would be 113.4 grams, so the shortcut is quite close.
Is the fluid ounce the same as the weight ounce?
No. A fluid ounce measures volume (about 29.5735 mL), while a weight ounce (avoirdupois ounce) measures mass (28.3495 grams). They are different units that happen to share a name. Use our volume converter for fluid ounce conversions.