Scaling a recipe is straightforward in theory: multiply every ingredient by the same factor. In practice, several ingredients — particularly seasonings, leaveners, and fat — do not scale perfectly in a linear fashion.
The Basic Scaling Method
- Determine your scaling factor: divide the number of servings you want by the original number.
- Original: 4 servings, Target: 10 servings → Factor: 10 ÷ 4 = 2.5
- Multiply every ingredient by this factor.
- Adjust seasonings to taste, since they rarely scale perfectly.
Ingredients That Don't Scale Linearly
Salt and spices: The palate's sensitivity to salt and spice doesn't scale. When doubling a recipe, start with 1.5× the salt and spice, then adjust. If tripling, start with 2× and taste.
Baking soda and baking powder: Scale leaveners by no more than the recipe factor for small recipes. For very large batches (4×+), you may need slightly less to avoid a chemical aftertaste.
Eggs: Eggs come in whole units, so scaling creates fractions. Round to the nearest whole egg and adjust liquid slightly to compensate. For very large batches, beat eggs and measure by weight or volume.
Cooking time: Cooking time does not scale linearly. A double batch of cookies might need the same bake time on the same-sized pans (just bake in more batches). A larger roast takes longer, but not twice as long.
Pan sizes: When doubling a cake recipe, don't double the pan size — use two pans of the original size instead.
Scaling Down: Halving a Recipe
Halving is often harder than doubling because of fractional eggs. For one egg: try 1 yolk + 1 teaspoon water, or beat the egg and use half the volume.
For very small amounts of leaveners (like ¼ tsp baking powder becoming ⅛ tsp), use a kitchen scale for accuracy — volume measurements become imprecise at this scale.
Tools That Help
A kitchen scale makes scaling dramatically easier. Instead of calculating "half of ¾ cup" (⅜ cup — try finding that mark on a measuring cup), simply weigh the original amount and halve the number.