How do I solve a proportion?

Fill three of the four values in A:B = C:D and leave one blank to solve for it.

Can this scale image dimensions?

Yes, the Scale dimensions tab keeps the original aspect ratio when resizing width or height.

How are ratios simplified?

By dividing both terms by their greatest common divisor.

Ratio Calculator

Solve, simplify, and scale ratios and aspect ratios.

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Ratio Calculator

Solve, simplify, or scale ratios

Leave one of C or D blank to solve for it.

Result

Updates live

Solved D

Solved C

—

Simplified ratio

2 : 3

As decimal

0.666667

Scaled width

800.00

Scaled height

450.00

About the Ratio Calculator

Solve proportions in the form A:B = C:D, simplify ratios to their lowest terms, and scale image or screen dimensions while preserving aspect ratio.

Examples

Simplify 24:36

24:36

Output

2:3

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Frequently asked questions

Version 1.0.0 · Updated 2026-08-06 · Runs entirely in your browser