DocomintCalculatrice de Rapport
Simplifiez un rapport à sa forme la plus simple, ou mettez-le à l'échelle d'une valeur cible.
What is a Calculatrice de Rapport?
Useful for scaling a recipe (a 2:3 flour-to-sugar ratio for 4 servings, scaled to 10) or reducing an odds/proportion statement to its simplest terms — a 24:36 mix simplifies the same way a fraction does, via the greatest common divisor.
How to use the Calculatrice de Rapport
- Choose Simplify or Scale to a target value
- Enter A and B (and a target value, for scaling)
- The result appears instantly, calculated on your device
Formula
Simplify: a:b → (a÷GCD):(b÷GCD) | Scale: a:b → target:(b × target÷a)
Simplifying divides both sides by their greatest common divisor. Scaling multiplies both sides by the same factor, so the proportion between them never changes.
Example
A recipe calls for a 24:36 (flour:sugar) ratio for one batch — simplified that's 2:3. Scaling A to a new batch size of 100g of flour keeps the ratio intact and returns 100:150, the correct amount of sugar for the larger batch.
Common mistakes
- Adding a fixed amount to both sides of a ratio instead of multiplying — a ratio scales proportionally, not by addition.
- Mixing up which number is A and which is B when reading a scaled result back into a real-world quantity.
- Treating a ratio like a percentage without first converting it (a 1:4 ratio isn't automatically "25%" without doing that conversion).
Frequently asked questions
How do you simplify a ratio?
Divide both numbers by their greatest common divisor, the same way you'd simplify a fraction. 24:36 has a GCD of 12, so dividing both sides gives the simplified ratio 2:3.
What's the difference between a ratio and a fraction?
A fraction represents a part of a whole (3 out of 4 slices). A ratio compares two separate quantities to each other (3 cups flour to 4 cups sugar) — they're simplified the same mathematical way, but describe different kinds of relationships.
Can I simplify a ratio with three or more terms, like 2:3:5?
Not currently — this tool works with two-term ratios (A:B) only. For a three-way ratio, simplify the first pair here, then check the third term against the same divisor by hand.
How do I scale both sides of a ratio, not just one?
Scale mode already does this — entering a new value for A automatically recalculates B to keep the exact same proportion, so both sides move together.
Is my numbers uploaded anywhere?
No — Calculatrice de Rapport runs entirely in your browser using JavaScript/WebAssembly. Your numbers is never sent to a server.