Recipe Scaling Calculator

Worked examples

The formula in plain words

Recipe scaling rests on one idea: keep the ratio between ingredients the same while changing the total quantity. To do that you find a single multiplier, called the scaling factor.

The scaling factor is desired servings divided by original servings. If a recipe serves 4 and you want 6, the factor is 6 divided by 4, which is 1.5. Every ingredient is then multiplied by 1.5. Two cups become three, one teaspoon becomes one and a half, and so on.

• Scaling factor = desired servings / original servings
• Scaled amount = original amount x scaling factor
• The same factor applies to every ingredient in the recipe

When to use it

This calculator is handy any time the batch size in front of you does not match the batch size you need. Cooking for a crowd, halving a recipe for one or two people, or converting a family recipe to a party quantity are all the same operation.

It also works for non-food ratios that scale linearly, such as batches of cleaning solution, garden fertiliser mixes, or any recipe-style formula where every component grows in proportion.

• Doubling or tripling for gatherings
• Halving or quartering to reduce leftovers
• Matching a recipe to the pan or dish you actually own
• Converting per-serving amounts to a total batch

What changes the answer most

The single biggest driver is the ratio of desired to original servings. A small change in either serving count shifts every ingredient. Double-check both numbers before you trust the result.

The starting ingredient amount matters too, but only linearly. Getting the original amount right, in consistent units, is what keeps the scaled figure meaningful.

• Original servings: the denominator, so errors here swing everything
• Desired servings: the numerator that sets your target batch
• Original ingredient amount: multiply after the factor is fixed
• Consistent units: measure the original in the unit you want the answer in

Things that do not scale in a straight line

Ingredient quantities scale cleanly, but several parts of cooking do not. Salt, spices, and strong flavourings often need less than the raw factor suggests, so taste and adjust rather than multiply blindly.

Cooking time, oven temperature, and pan surface area follow their own rules. A double batch in the same pan is deeper and cooks slower; spreading it across two pans keeps the timing closer to the original. Leavening agents like baking soda can also behave differently at large multiples.

• Season to taste rather than exactly by the factor
• Larger volumes may need longer, gentler cooking
• Use pans that keep a similar depth to the original
• Very large or very small factors may need recipe testing

Common mistakes

The most frequent error is swapping the two serving numbers, which flips scaling up into scaling down. Read the labels carefully: original goes on the bottom, desired on the top.

People also mix units, multiplying a metric amount by a factor derived from an imperial recipe, or forget to apply the same factor to every ingredient. Calculate one ingredient here to confirm the factor, then apply that factor to the whole list.

• Reversing original and desired servings
• Applying the factor to some ingredients but not others
• Mixing measurement units within one recipe
• Rounding before finishing the calculation instead of after

What this assumes

• Every ingredient scales linearly in direct proportion to servings.
• Original and desired servings are measured the same way (portions of equal size).
• The ingredient amount is entered in the unit you want the answer in.
• Seasoning, timing, and pan size are not adjusted by the calculator.