Recipe Scaler: Resize Any Recipe by Servings

How the recipe scaler works

The scale factor is new servings ÷ original servings. Every line that starts with a number is multiplied by that factor; the rest of the line, including the unit and the ingredient name, is left alone. Lines without a leading number, like "pinch of salt" or "zest of 1 lemon", pass through unchanged so you can decide how to handle them.

The scaler reads whole numbers (2), decimals (1.5), simple fractions (3/4), mixed numbers (1 1/2), and Unicode fractions (½, 1¾) that show up when you copy from recipe sites. Results are rounded to the nearest eighth or third, the marks on US measuring cups and spoons, so you get 3 3/8 cups instead of 3.375.

Worked example: 4 servings to 6

The factor is 6 ÷ 4 = 1.5. A chocolate chip cookie recipe with 2 1/4 cups flour becomes 2.25 × 1.5 = 3.375 cups, shown as 3 3/8 cups. Measuring 3/8 cup is awkward, so use the conversion table: 1/8 cup is 2 tablespoons, so 3 3/8 cups is 3 cups plus 6 tablespoons.

3/4 cup sugar becomes 1 1/8 cups, which is 1 cup plus 2 tablespoons. 1/2 teaspoon salt becomes 3/4 teaspoon. 2 eggs become 3. Clean numbers are rare, which is exactly why a scaler beats doing it in your head while the oven preheats.

US measurement conversions worth memorizing

3 teaspoons = 1 tablespoon. 16 tablespoons = 1 cup. So 1/4 cup = 4 tablespoons, 1/3 cup = 5 tablespoons plus 1 teaspoon, and 1/2 cup = 8 tablespoons. 2 cups = 1 pint, 4 cups = 1 quart, 4 quarts = 1 gallon. 1 stick of butter = 8 tablespoons = 1/2 cup = 4 ounces.

When a scaled amount lands between marks, convert down a unit. 5/8 cup is 10 tablespoons. 1 1/2 tablespoons is 1 tablespoon plus 1 1/2 teaspoons. For baking, a kitchen scale removes the problem entirely: 1 cup of all-purpose flour weighs about 120 to 125 grams depending on how it is spooned, and grams scale with no rounding at all.

What does not scale in a straight line

Pan size. Pan capacity follows area, not width. An 8x8 pan is 64 square inches; a 9x13 is 117. Doubling an 8x8 recipe gives 128 square inches of batter, so a 9x13 will be slightly thicker and may need a few extra minutes. A 9-inch round is about 63.6 square inches, nearly the same as an 8x8 square.

Cooking time. Time depends on thickness and oven load, not quantity. Two pans of cookies bake in the same time as one, though you should rotate them. A roast twice as heavy does not take twice as long; cook to internal temperature. USDA guidance is 165°F for poultry, 160°F for ground beef and pork, and 145°F plus a 3-minute rest for whole cuts of beef, pork, veal, and lamb.

Seasoning and alcohol. Salt, cayenne, and garlic can taste stronger in big batches because less evaporates. Wine in a sauce reduces based on surface area, not volume. Scale these conservatively and taste before serving.

Eggs, yeast, and other awkward ingredients

Eggs: a US large egg is about 50 grams out of the shell, roughly 3 tablespoons beaten. For half an egg, beat one and measure 1 1/2 tablespoons. For baking, whisk the egg and weigh it for accuracy.

Yeast: scale it exactly for bread, but know that a big dough rises faster because it holds heat. Watch the dough, not the clock. A standard packet of active dry yeast is 2 1/4 teaspoons (7 grams), which is useful when a scaled recipe calls for 1.5 packets.

Cans: "1 can (15 oz) beans" scales to "1.5 can (15 oz)". The scaler multiplies the first number only, so keep can sizes in parentheses after the count, as shown, to avoid scaling the size by mistake.

Common mistakes

Putting the ingredient before the amount ("flour, 2 cups") so the number is not at the start of the line. Scaling a recipe for a crowd by 5x or more in one pot, which rarely cooks evenly; split it into batches instead. And forgetting that serving sizes in recipes are often generous or stingy. If a recipe that "serves 4" feeds your family of four with nothing left, set the original servings to 3 before you scale.