∶ Math Calculator

Ratio Calculator

Simplify ratios, find equivalent ratios, scale ratios up or down, and solve for a missing value in a proportion — all in one tool.

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Simplify, scale, or solve missing values in any ratio or proportion.

Frequently Asked Questions

How do you simplify a ratio?
Divide both parts of the ratio by their Greatest Common Divisor (GCD). For example, 6:9 → GCD(6,9)=3 → 6÷3 : 9÷3 = 2:3.
What is a proportion?
A proportion states that two ratios are equal: A/B = C/D. If three values are known, the fourth can be found by cross-multiplication: D = B×C÷A.