Ratio Calculator
Simplify and scale ratios
About the Ratio Calculator
Ratios express how quantities relate — 3:2, 16:9, 1:4 — and working with them means simplifying, scaling, or solving for a missing part. This calculator simplifies a ratio to its lowest terms, scales it by any factor, and even handles three-part ratios.
Cooks scale recipes, designers reason about aspect ratios, and students simplify ratios for homework. Builders and hobbyists use it for mixing ratios like paint or concrete. Because it accepts an optional third value and a scale factor, it goes beyond simple two-part reduction to the practical cases people actually meet.
How to Use the Ratio Calculator
- Enter the ratio values in fields A and B (and C for a three-part ratio).
- Read the simplified ratio, reduced to its lowest whole-number terms.
- Enter a scale factor to multiply the ratio up or down.
- Check the scaled ratio and, for two-part ratios, the fraction form, plus the step-by-step working.
Why Use ToolForge’s Ratio Calculator
- It supports three-part ratios (A:B:C), not just two terms, covering mixes and proportions other tools cannot.
- It both simplifies and scales — reducing to lowest terms and multiplying by a factor — in one place.
- It shows the greatest-common-divisor steps behind the simplification, so the reduction is transparent.
- It runs entirely client-side with no account.
Frequently Asked Questions
How do you simplify a ratio?
You divide every term by their greatest common divisor, the same way you reduce a fraction. For 12:8, the GCD is 4, so it simplifies to 3:2. The calculator finds the GCD across all terms and shows the division.
How do I scale a ratio up or down?
Multiply each term by the same factor. To double 3:2 you get 6:4; to triple it you get 9:6. Enter a scale factor and the calculator applies it to every part of the simplified ratio.
What is the difference between a ratio and a fraction?
A ratio compares quantities (3:2 means three parts to two), while a fraction expresses a part of a whole (3/5). They are related — the calculator shows a two-part ratio as a fraction — but a ratio can have more than two terms, which a single fraction cannot.
How do I keep a ratio the same when changing one quantity?
Multiply or divide every term by the same number so the proportion holds. If a 2:3 paint mix needs 6 units of the first color, scale by 3 to get 6:9. Enter your ratio and a scale factor and the calculator works out the matching amounts.
