How it works
How Recipe Scaler solves the problem
Think of Recipe Scaler as the back-of-the-envelope version of the calculation, only the envelope is a web page and the arithmetic is audited by our test suite.
Baking is chemistry — swap ingredients and the texture tells on you. Read the recipe to the end first — then scale the recipe and the rest of this page explains what the answer means.
Multiply every ingredient by the scale factor (wanted servings ÷ original servings). Baking times scale less than linearly — roughly × cube-root of volume ratio for cakes.
Seeing it on real numbers
A working example keeps the formula honest:
Multiply every ingredient by the scale factor (wanted servings ÷ original servings). Baking times scale less than linearly — roughly × cube-root of volume ratio for cakes.
Moments this tool earns its keep
Recipe Scaler is aimed at people arriving with questions like these:
- "How to scale a recipe"
- "Double recipe"
- "Halve recipe"
- "Servings calculadora"
- "What is recipe scaler"
- "How to calculate recipe scaler"
Where the number stops being useful
Every tool has an edge where it stops being the right answer. Recipe Scaler is no exception:
- For legally binding tax or medical decisions — cross-check with HMRC, NHS or a qualified professional.
- For very large or very small extremes the rounding error outgrows the useful precision.
- When the underlying rate or threshold has changed since the page was last reviewed — always verify with the primary source.
- When the input you have is already a derived figure (net of something) — feeding it in as "gross" will double-subtract.
Traps to steer around
Every time you scale the recipe for a new scenario, one of these creeps in — it's worth knowing them ahead of time.
- Assuming the UK and US versions of the same unit are interchangeable — they're not.
- Typing a comma where the tool expects a dot (or vice versa).
- Rounding early — particularly painful in percentages and compound growth.
- Ignoring the time window: a 'per year' answer makes no sense with a monthly input.
- Treating the answer as private: screenshots are fine, but the URL always reruns cleanly.
The sources behind the numbers
Where the maths needs an external authority, we cross-check against:
- BBC Good Food
- Good Housekeeping
- Delia Online
Works well alongside
If this question keeps coming up for you, the same cluster of tools usually comes next:
- Grams to Cups Converter — Convert grams to cups for flour, sugar, butter, rice and more — density-aware, because 1 cup of flour ≠ 1 cup of sugar.
- Oven Temperature Converter — Convert between °C, °F, gas marks and fan/conventional oven settings — with the standard UK reduction of 20 °C for fan ovens.
- Rule of Three calculadora — Solve a proportion by cross-multiplication — the classic rule-of-three used for recipe scaling, unit pricing and percent conversions.
How we keep this accurate
Our calculadoras run on pure, unit-tested functions — the same logic lives in the browser and in the CI test suite. When tax rates, thresholds or official figures move, the update lands within 24 hours of the announcement. You can read the editorial policy and corrections policy.
Found an out-of-date number on Recipe Scaler or anywhere else in the Cooking toolkit? Send it to the editorial desk and we'll patch it. Or browse the full calculadora directory for the next tool you need.