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Scaling guide

How to double a recipe,
properly.

Doubling is the friendliest scaling direction — fewer rounding problems than halving, and the recipe almost always already 'works' at 2×. The traps are pan choice, salt/spice scaling (which isn't linear), and cooking time (which scales by volume for liquids, by the cube root for solid bakes). This guide gives the doubled quantities of every common measure, the seasoning rule professional kitchens follow, and the pan-size math so your doubled cake actually fits the oven.

The math, with a worked example

Every recipe scales by the same rule: multiply each ingredient by the ratio. For doubled recipes that's ×2. The tricky cases are the ones where the linear math hits the realities of measuring tools, eggs, and seasoning perception.

Doubling a recipe with 1 cup flour, ½ cup butter, 2 large eggs, 1 tsp salt: flour → 2 cups, butter → 1 cup, eggs → 4 large, salt → 1½ tsp (not 2 tsp). Pan: a recipe written for an 8″ round (50 in² area) doubled needs ~100 in², which fits a 9 × 13″ rectangle (117 in²) or an 11″ round (95 in²).

The three pitfalls of doubled recipes

1. Don't double salt and spices linearly

Salt and spices scale non-linearly with quantity — at 2×, use 1.5× the original amount, then taste and adjust. The bigger the recipe, the more it concentrates flavour because less surface area is exposed to air.

2. Double the pan area, not the pan diameter

A 9 × 13″ pan has roughly twice the area of an 8″ round. Two 8″ rounds baked side-by-side is the easier solution if you don't have a bigger pan — they bake in about the same time as a single one.

3. Cooking time goes up, but not by 2×

Liquids (soups, stews) scale roughly linearly. Solid bakes (cakes, breads) scale by the cube root of the volume change — doubling a cake adds about 26 % to the bake time, not 100 %. Check 5 minutes before the original time.

When NOT to double a recipe

Doubling works fine for almost every recipe except yeast doughs — bread dough rises differently in different masses, and a doubled batch may over-proof while still in the bowl. For bread, make two separate batches sequentially rather than one doubled batch.

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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