Beyond homework

Recipe scaling with proportions

Adjust ingredient amounts for a different number of servings.

Recipe scaling is a practical use of direct proportion. If you want more servings and keep the ingredient balance unchanged, multiply every ingredient amount by the same serving factor.

From 4 servings to 6

The factor is 6 ÷ 4 = 1.5. A recipe calling for 2 cups of rice, 3 cups of water, and 1 teaspoon of seasoning scales to 3 cups, 4.5 cups, and 1.5 teaspoons respectively. This is arithmetic scaling; suitability still depends on the recipe.

Enter it as a proportion

Place the original ingredient amount in a and the original servings in b. Put the new servings in d and leave c blank. For 2 cups across 4 servings, changing to 6 servings gives 2/4 = x/6. The result is x = 3 cups.

Keep familiar kitchen fractions

Scaling 3/4 of a cup by 2/3 gives 1/2 cup. Enter 3/4 directly rather than rounding it. The calculator accepts fractions and mixed numbers, so an amount like 1 1/2 cups does not need to be converted by hand. See fractional proportions for details.

What the calculation cannot decide

Oven temperature and cooking time generally should not be multiplied by the serving factor. Changing a pan's depth or shape changes heat transfer. Spices, thickening agents, and some baking ingredients may need adjustments beyond simple scaling. Use the recipe author's guidance where available.

Keep the units consistent for each ingredient. A cup is a volume measure; converting cups to grams requires an ingredient-specific density. The calculator does not know whether your number represents flour, water, or sugar and cannot perform that conversion implicitly.

This example also explains why these tools are useful beyond students: cooks, hobbyists, designers, and anyone adjusting quantities can use ratios. For more contexts, read word problems and unit rates.