How to convert a US recipe to metric
Short answer
Convert weights directly (1 oz = 28.3 g, 1 lb = 454 g). Convert cups to grams only for ingredients with a reliable density, like flour (120 g) or sugar (200 g). For everything else, convert cups to millilitres (1 cup = 237 ml). Recepti follows these same rules when you choose metric.
The three rules
- Weight to weight is always safe. Ounces and pounds convert to grams with a fixed ratio.
- Volume to volume is always safe. Cups, tablespoons and teaspoons convert to millilitres.
- Volume to weight needs a density. A cup of flour and a cup of honey weigh very different amounts. Only convert when you know the value.
| US weight | Metric |
|---|---|
| 1 ounce | 28.3 g |
| 4 ounces | 113 g |
| 8 ounces | 227 g |
| 1 pound | 454 g |
| 2 pounds | 907 g |
| US volume | Metric |
|---|---|
| 1 teaspoon | 4.9 ml |
| 1 tablespoon | 14.8 ml |
| 1 fluid ounce | 29.6 ml |
| 1/4 cup | 59 ml |
| 1/3 cup | 79 ml |
| 1/2 cup | 118 ml |
| 1 cup | 237 ml |
| 4 cups | 0.95 l |
Common staples by weight
For flour, sugar, butter and other staples, use the cups to grams chart.
Let Recepti do it
Pick Metric (g, ml, °C) when you first open Recepti. Imported recipes are shown in metric where a safe conversion exists. If an ingredient has no reliable density, it is shown in millilitres rather than guessed in grams.
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Questions
Why not convert every cup to grams?
Because every ingredient has a different density. A wrong conversion is worse than none.
Is a US cup the same as a metric cup?
No. A US cup is about 237 ml; a metric cup is 250 ml. Recipes from the US use the US cup.