Recipe Scaler
Scale a recipe up or down to any number of servings, ingredient by ingredient.
Good to know. Double the flour, double the eggs, but not quite double the salt or the baking time.
How it works
In plain words
Divide the servings you want by the servings the recipe makes. Multiply every amount by that factor.
The formula
factor = servings wanted ÷ recipe servings new amount = amount × factor
Worked example
From 4 to 6 servings, multiply by 6 ÷ 4 = 1.5: 300 g flour, 3 eggs, 2 ¼ cups milk, ¾ tsp salt and 45 g butter.
Sources
No outside data or rates: this is plain arithmetic.
4 automated tests check its answers on every change.
About the recipe scaler
Most recipes serve four, and most dinners don’t. Paste the ingredient list, say how many the recipe serves and how many you are cooking for, and every quantity is scaled for you, including the awkward ones like 1 ½ cups or ⅓ teaspoon.
Each line should start with the amount, in grams, cups, spoons or plain numbers like “2 eggs”. The unit and ingredient are kept as they are. Results are written as kitchen fractions (¼, ⅓, ½, ⅔, ¾) when they come out close to one, so you don’t have to measure 0.67 of a cup. Lines without an amount, like “salt to taste”, are left alone.
Scaling is mostly proportional, with a few exceptions worth knowing. Salt, spices and strong flavours are better scaled a little less and adjusted to taste. Eggs can’t be split easily; round to the nearest whole egg, or beat one and use part of it. Baking times don’t scale with the amount: a bigger cake in a bigger tin needs a bit longer, but not twice as long, while more muffins in the same tins need the same time.
For converting cups into grams, or ounces into millilitres, use the cooking converter. For scaling by a ratio rather than servings, such as a recipe for a 20 cm tin in a 24 cm tin, the factor is the ratio of the areas: (24 ÷ 20)² = 1.44.
Questions people ask
How do I scale a recipe?
Divide the servings you want by the recipe’s servings, and multiply every ingredient by the result. From 4 to 6 servings, multiply by 1.5.
How do I halve a recipe with 3 eggs?
Use 1 ½ eggs: one whole egg plus half of a second, beaten. Or round to 2 small eggs.
Do I change the cooking time when I double a recipe?
Not by double. Bake at the same temperature and check early; a deeper dish needs somewhat longer.