1 avoirdupois ounce equals 28.3495 grams. This is the exact factor defined by NIST and used in all US kitchen scales and food packaging. Whether you are following a European recipe that lists ingredients in grams or checking a nutrition label, the conversion is straightforward: multiply ounces by 28.3495.
The formula
g = oz × 28.3495
To convert back from grams to ounces, divide by 28.3495:
oz = g ÷ 28.3495
Practical examples
Example 1 — Weighing butter for a French recipe
A croissant recipe calls for 200 g of cold butter. Your block of butter is labeled in ounces.
200 ÷ 28.3495 = 7.05 oz
Cut just over 7 ounces from the block.
Example 2 — Converting a US recipe to metric
An American brownie recipe calls for 6 oz of dark chocolate. You are in the UK and your scale reads in grams.
6 × 28.3495 = 170.1 g
Example 3 — Nutrition labels
A serving size on a US snack is listed as 1 oz. You want to know the gram equivalent for a food tracker that uses grams.
1 × 28.3495 = 28.35 g (nutrition labels conventionally round to 28 g)
Weight ounces versus fluid ounces
This is the most common source of confusion in cooking unit conversions.
- Weight ounces (oz) measure mass — they tell you how heavy something is. Used for flour, butter, chocolate, meat, and produce. 1 oz = 28.3495 g.
- Fluid ounces (fl oz) measure volume — they tell you how much space a liquid occupies. Used for water, milk, and other pourable liquids. 1 US fl oz = 29.574 ml.
A recipe that says "4 oz of flour" means 4 weight ounces = 113.4 g. A recipe that says "4 fl oz of milk" means 4 fluid ounces = 118.3 ml. The two are not interchangeable.
Quick reference: ounces to grams
| Ounces | Grams |
|---|---|
| ¼ oz | 7.09 g |
| ½ oz | 14.17 g |
| 1 oz | 28.35 g |
| 2 oz | 56.70 g |
| 3 oz | 85.05 g |
| 4 oz (¼ lb) | 113.40 g |
| 6 oz | 170.10 g |
| 8 oz (½ lb) | 226.80 g |
| 10 oz | 283.50 g |
| 12 oz (¾ lb) | 340.19 g |
| 16 oz (1 lb) | 453.59 g |
Why European recipes use grams
Grams are more precise than volume measurements like cups and ounces for baking. Flour, in particular, compresses differently depending on how it is scooped — a "cup" of flour can range from 120 g to 160 g depending on packing. A recipe that specifies 150 g of flour removes that ambiguity entirely. Many professional bakers in the US now use gram weights for this reason.
If you bake often from both US and European sources, a digital kitchen scale that switches between ounces and grams is worth the investment.
For a single-page cooking reference covering volume conversions, oven temperatures, butter equivalents, and common ingredient gram weights, see the Complete Cooking Conversion Chart →.