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ScaleRecipe

Scaling guide

How to halve a recipe,
properly.

Halving a recipe is the most common scaling task in home kitchens — recipes are written for four, you're cooking for two. The math is trivial in the abstract (multiply by 0.5) but gets fiddly with the units cooks actually use: cups, teaspoons, sticks of butter. This guide gives the exact fraction-aware halves of every common quantity, the egg and salt cases that need special handling, and the small number of recipes where you should choose a different scaling approach entirely.

The math, with a worked example

Every recipe scales by the same rule: multiply each ingredient by the ratio. For halved recipes that's ×0.5. The tricky cases are the ones where the linear math hits the realities of measuring tools, eggs, and seasoning perception.

Halving a recipe with 1½ cups flour, ⅔ cup sugar, 3 large eggs, and 1 tsp salt: multiply each by 0.5. Flour: ½ × 1.5 = 0.75 cup = ¾ cup. Sugar: ½ × ⅔ = ⅓ cup. Eggs: 1.5 large eggs (weigh 75 g of beaten egg). Salt: ½ tsp.

The three pitfalls of halved recipes

1. Half an egg

1.5 eggs isn't a number. Beat one egg, weigh 25 g (half of a 50 g large egg), use that. The remaining 25 g goes into tomorrow's scrambled eggs or down the drain.

2. Baking soda and salt: round, don't truncate

Halving ½ tsp baking soda gives ¼ tsp — easy. Halving ¾ tsp gives ⅜ tsp which has no standard measure. Use a digital scale, or round to ⅓ tsp (4 splits between ¼ and ½ are imperceptible at sub-teaspoon volumes).

3. Cooking time barely changes

Halving a soup roughly halves the time. Halving a cake reduces the bake by ~20 % (cube-root rule). Halving cookies on a sheet pan: same time. The math that scales ingredients does NOT apply to cooking time.

When NOT to halve a recipe

Halve cakes, cookies, sauces, and soups freely. Don't halve bread, pizza dough, or anything yeast-leavened unless you've made the original recipe several times — small doughs are temperature-sensitive and proof differently from larger ones. For yeast bakes, freeze the leftover half-loaf instead.

Skip the math

Use the scaler instead

The math above is exactly what ScaleRecipe's scaler does automatically — paste any recipe, set the original servings and the target, and every line is rewritten with proper culinary fractions and smart unit promotion. Cooking-time adjustment is documented separately because it scales differently from ingredients.

Open the scaler →Cooking-time guide

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