Simplify a ratio
Both parts are divided by their GCD — 12:8 reduces to 3:2 — with a percentage split shown alongside.
Math calculators
Ratio Calculator
Simplify ratios, solve proportions, or scale by any factor.
Complete guide
How to use Ratio Calculator
Pick a mode: simplify a ratio to lowest terms, solve a proportion for the missing value (A:B = C:?), or scale a ratio up or down by a factor. Results include a percentage breakdown where relevant.
Simplification uses the greatest common divisor so 12:8 becomes 3:2. Proportions are solved by cross-multiplication.
Solve a proportion
Know three of four values in A:B = C:D? The calculator cross-multiplies to find the missing one.
Scale a ratio
Multiply both sides of a ratio by any factor to scale a recipe, a mix, or a model.
Answers
Ratio Calculator FAQs
How do I simplify a ratio?
Divide both parts by their greatest common divisor. 12:8 simplifies to 3:2 (GCD = 4).
What is a proportion?
A statement that two ratios are equal: A:B = C:D. Given three values, the tool solves for the fourth.
What is 3:1 as a percentage?
3:1 means 75% to 25%, because 3/(3+1) = 75%.
Can I use decimals?
Yes. Enter decimal values for A and B and the simplification works as a decimal ratio.
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