Recipe scaler

How do I scale a recipe?

Divide the servings you want by the servings the recipe makes, and multiply every amount by that number. Going from 4 to 6 servings is × 1.5: 2 cups of flour becomes 3 cups.

How do I halve ⅓ cup?

Half of ⅓ cup is 2 tablespoons plus 2 teaspoons — ⅓ cup is 16 teaspoons, so half is 8. The scaler switches to spoons automatically when an amount drops below ¼ cup.

What do I do with half an egg?

Beat one egg and use half of it. For larger batches round to whole eggs and adjust with a little liquid if the batter looks dry.

Do baking times change when I scale a recipe?

Often, yes. A bigger batch in a deeper pan bakes longer; the same batter split into more pans bakes in about the original time. The cake pan converter works out the batter for a different pan.

Which lines does it leave alone?

Lines without a number at the start, like "salt to taste" or "oil for frying", are kept as they are. Ranges like "2–3 cloves" are scaled at both ends.

How do I scale a recipe for a different pan?

Compare the pan areas. A 9-inch round pan has an area of 63.6 square inches, an 8-inch round 50.3 and a 10-inch round 78.5. An 8-inch pan therefore holds about 79% of the batter for a 9-inch pan, and a 10-inch pan needs about 1.23 times as much. A 9 × 13 inch rectangular pan is 117 square inches.

How the scaling works

The scale factor is the number of servings you want divided by the number the recipe makes. Every amount that has a number in front of it is multiplied by that factor, and fractions are converted to the nearest convenient kitchen measure. Cups and spoons are re-expressed in smaller units when the result is small, so one third of a cup halved becomes 2 tablespoons plus 2 teaspoons. A line without a leading number, such as “salt to taste”, stays as written.

Worked examples

Scaling by 1.5: “2 cups flour” becomes “3 cups flour”, “1 1/3 cups sugar” becomes “2 cups sugar”, “1/2 tsp salt” becomes “¾ tsp salt” and “3 eggs” becomes “4 ½ eggs”. Scaling by 0.5: “1 tbsp butter” becomes “1 ½ tsp butter” and “2-3 cloves garlic” becomes “1–1 ½ cloves garlic”. For eggs, beat one and measure out the fraction you need.

Things the scaler cannot know

Package sizes written in parentheses are not scaled: “1 can (14 oz) tomatoes” scaled by 1.5 becomes “1 ½ can (14 oz) tomatoes”, so read the can size as a note and work out the total yourself (21 oz in this case). Cooking times, pan size, oven temperature and rising times do not scale with the ingredients; a double batch in the same pan is twice as deep and bakes longer, while the same batter spread over a larger area bakes faster. Season larger batches in stages and taste, rather than multiplying salt and spices blindly.

Common mistakes

Scaling only some of the ingredients leaves the recipe out of balance, so enter every line, including the small ones. Converting between cups and weight is another trap, since a cup of flour and a cup of sugar weigh different amounts; scale in the same unit as the recipe and convert afterward. Finally, a factor like 1.5 on an egg count gives half eggs, so decide whether to round or to beat and divide an egg.

Sources: the proportional scaling used in standard cooking references; pan areas from the area of a circle, πr². The volume equivalents (3 teaspoons to a tablespoon, 16 tablespoons to a cup) are the US customary kitchen measures given in NIST Handbook 44. Related: cake pan converter, cooking measurement converter, baker’s percentage calculator and recipe resizer.