A ratio compares two quantities and shows how many times one value contains another. For example, 4:2 simplifies to 2:1.

How do I calculate ratios?

To calculate a ratio, divide both numbers by their greatest common divisor. To scale a ratio, multiply each part by the same factor.

Ratio Calculator | Convert, Scale and Simplify Ratios Online

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How it works

Math helper

This ratio calculator solves problems of the form A:B = C:D. Enter any three values and leave one field empty. The empty value is calculated automatically.

Typical uses

Common aspect ratios

All calculations run in your browser. No data is sent to a server. Recent results are stored only in this device using localStorage.