The exact equivalent
An ounce is exactly 28.349523125 grams, because a pound is defined as exactly 0.45359237 kg and holds 16 ounces.
1 oz = 28.34952313 g
1 g = 0.03527396 oz
How to convert it by hand
Just multiply by the conversion factor. To go from ounces to grams, multiply by 28.349523; to come back, divide by that same number or multiply by 0.035274.
For example: 25 oz × 28.349523 = 708.7381 g.
A tip that saves mistakes: check the result goes the way you expect. If grams are a smaller unit than ounces, the number has to come out bigger. If it comes out smaller, you divided when you should have multiplied.
Conversion table
| oz | g |
|---|---|
| 1 | 28.3495 |
| 2 | 56.699 |
| 5 | 141.7476 |
| 10 | 283.4952 |
| 20 | 566.9905 |
| 50 | 1,417.4762 |
| 100 | 2,834.9523 |
Reference points to picture it
| Reference | Equals |
|---|---|
| 1 ounce | 28.35 g |
| 4 ounces (a quarter pound) | 113.4 g |
| 8 ounces (half a pound) | 226.8 g |
| 16 ounces (a pound) | 453.6 g |
The trick for doing it in your head
Multiply by 28 and add 1%. For 8 ounces: 8 × 28 = 224, plus a little, gives 227 g.
It is fine for getting by without a phone, but not for anything that depends on precision: in a recipe, on a building site or in a dose, use the exact conversion.