Converting American Recipes to Metric

What actually needs converting

An American recipe usually mixes four kinds of measurement: volume (cups, tablespoons, teaspoons, fluid ounces), weight (ounces and pounds), temperature (Fahrenheit) and size (inches for pans). Each one converts differently, and the most common mistake is treating them all as a simple multiplication.

Work through the recipe in order: list the ingredients, convert them one by one, then deal with the pan and the oven. Writing the metric amount beside each original line keeps the recipe readable and lets you check your arithmetic later.

Liquids: cups to milliliters

Liquids convert directly from volume to volume. A US cup is 236.588 mL, a tablespoon is about 14.8 mL and a teaspoon is about 4.9 mL. Most cooks round these to 240 mL, 15 mL and 5 mL, and that rounding is fine for milk, water, stock or cream.

Be aware that a metric cup is a separate unit of exactly 250 mL, about 5.7% larger than a US cup. Metric recipes written for 250 mL cups and American ones written for 236.588 mL cups are not the same, so convert using the US figure when the source is American. Fluid ounces work similarly: one US fluid ounce is 29.57 mL.

Dry ingredients: cups to grams

Dry ingredients are different, because a cup holds a different weight of each one. Convert them by multiplying the number of cups by the ingredient’s weight per cup. Typical values for a US cup are:

• All-purpose flour: 120 g
• Granulated sugar: 198 g
• Packed brown sugar: 213 g
• Powdered sugar: 113 g
• Butter: 227 g
• Rolled oats: 89 g
• Cocoa powder: 84 g

Charts differ by a few grams, and some give a different weight for a cup of flour. For baking, rounding to the nearest 5 g is sensible for bulk ingredients. Small amounts of salt, baking powder and spices are easiest to keep in teaspoons and tablespoons, since many kitchen scales read only in whole grams. Metric teaspoons and tablespoons are 5 mL and 15 mL, close enough to the US versions for these small quantities.

Ounces and pounds to grams

Weights are simpler because they are exact. One ounce is 28.349523125 g and one pound is 453.59237 g. For recipe work, 28.35 g per ounce and 454 g per pound are accurate enough. A recipe that calls for 8 oz of chocolate needs 227 g, and 1½ lb of potatoes is about 680 g.

Many cooks round to a friendlier number, such as 225 g for 8 oz or 450 g for a pound. That is common practice and works well in most dishes, but if you are scaling a recipe, pick one rounding style and keep it consistent so proportions stay the same.

Pan sizes and oven temperatures

An inch is exactly 2.54 cm. A 9-inch round pan is therefore 22.9 cm, so a 23 cm pan is the nearest standard size, and an 8-inch pan is 20.3 cm, close to a 20 cm pan. A 9 × 13 inch pan is about 23 × 33 cm. Check the depth too, since a shallower pan changes baking time.

For temperatures, subtract 32 from Fahrenheit and multiply by 5/9. That gives 350 °F as 176.7 °C, which recipes and oven dials round to 180 °C (a converter that rounds to whole degrees shows 177 °C). Recipes commonly pair 325 °F with 170 °C, 375 °F with 190 °C, 400 °F with 200 °C and 425 °F with 220 °C. Fan ovens often need a lower setting than conventional ones; follow your oven’s manual for the exact reduction.

A worked example

Take a simple cookie recipe: 2¼ cups flour, 1 cup butter, ¾ cup granulated sugar, ¾ cup packed brown sugar, 2 eggs, 1 tsp baking soda, baked at 350 °F.

1. Flour: 2.25 × 120 = 270 g.
2. Butter: 1 × 227 = 227 g.
3. Granulated sugar: 0.75 × 198 = 148.5 g, rounded to 150 g.
4. Brown sugar: 0.75 × 213 = 159.75 g, rounded to 160 g.
5. Eggs: leave as 2; count-based ingredients need no conversion.
6. Baking soda: keep as 1 tsp, or use 5 mL.
7. Oven: 350 °F is about 180 °C.

The metric version reads 270 g flour, 227 g butter, 150 g granulated sugar, 160 g brown sugar, 2 eggs, 1 tsp baking soda and a 180 °C oven. A cooking converter such as this one can do the cups-to-grams and temperature steps quickly if you prefer not to calculate by hand.

Tips for reliable results

Convert once, then cook from the converted list rather than switching between systems halfway through. Write the metric amounts directly on the recipe, and note the ingredient weights you used so you can adjust them next time.

If the result seems off, the usual culprits are a cup of flour that was packed or scooped heavily, brown sugar that was not packed, or a source that used a different cup size. Because chart values vary a little, treat the first conversion as a starting point and change the amounts if the dough or batter looks noticeably wetter or drier than the original recipe describes.