Recipe Scaler

Using the Recipe Scaler

Point the scaler at a recipe you already have and tell it how many servings you want instead. It recalculates every ingredient to hold proportions exactly and renders friendly kitchen fractions wherever the math cooperates.

1. Original servings - the number printed on the recipe.
2. Target servings - what you actually want to make.
3. Ingredients - add each row with name, amount, and unit (cups, tablespoons, teaspoons, fluid ounces, grams, kilograms, millilitres, or litres).
4. Scale Recipe - the button runs the math and shows a side-by-side table of original and scaled amounts.

What the Scaler Does Under the Hood

The core operation is a scale factor of target / original applied to every amount. For 4 servings scaled to 10, the factor is 2.5 - 1 cup becomes 2.5 cups, 1.5 tsp becomes 3.75 tsp (rendered as 3 3/4 tsp). The fraction rendering compares the decimal part against common denominators (2, 3, 4, 6, 8, 16) and picks the closest match under a small tolerance. Arithmetic runs on JavaScript IEEE 754 doubles, which is more than accurate enough - kitchen scales round to the gram anyway.

Real Moments the Scaler Earns Its Keep

• Thanksgiving dinner for 12 from a pie recipe written for one 9-inch pie.
• Halving a four-serving pasta recipe because it is just you tonight.
• Batch-cooking chilli or curry - 5x a standard recipe into a Dutch oven.
• Converting an old family recipe that feeds 20 down to a household casserole.
• Bread dough when you have enough flour for 1.5 loaves, not 2.
• Scaling a cocktail recipe from 1 serving to a pitcher for 8.

Where Linear Scaling Breaks Down

Spices do not scale linearly. Tripling a recipe often calls for 2.5x the salt, not 3x - start at 75% of the scaled amount and taste up. Baking is worse: leavening agents scale imperfectly because gas release depends on surface area and oven dynamics. Eggs are a whole-unit problem - 2.5 eggs means beating three and using weight (a large egg is 50 g without the shell). Thickeners like cornstarch have a nonlinear relationship with liquid volume. Cooking vessel size and evaporation change with scale, which affects cook time. The calculator gets the ingredient list right; the cook adjusts technique.

A Short Lesson in Kitchen Fractions

US kitchen measurements form a specific ladder: 3 tsp equal 1 tbsp, 16 tbsp equal 1 cup, 2 cups equal 1 pint, 4 quarts equal 1 gallon. Within that system, fractions like 1/8, 1/4, 1/3, 1/2, 2/3, and 3/4 cup correspond to physical measuring cups. A scaled value like 0.875 cups ideally rounds to 7/8 cup, but nobody has an 7/8-cup measure - most cooks use 3/4 + 2 tbsp instead. Metric recipes (grams, millilitres) scale cleanly because there is no fractional conversion step. If you can, scale a metric recipe with a kitchen scale - it is far more precise than volumetric cups, especially for flour where packing density alone swings volume by 20%.

How the Scaler Compares to Alternatives

Most recipe apps (Paprika, NYT Cooking, AllRecipes) include built-in scaling but lock it to recipes in their database. A spreadsheet column with =A2 * $B$1 gives full control but no fraction rendering. A kitchen scale plus a gram-first recipe is most accurate for baking. This scaler is the fastest option when you have a printed or web recipe in cups-and-teaspoons and want the scaled numbers in the same units, without retyping the whole recipe into an app. It will not convert volume to weight; for that use King Arthur's ingredient weight chart.