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.

Is my data uploaded to a server?

No. This tool runs entirely in your browser using standard web APIs, so your input never leaves your device and nothing is logged or stored on our servers.

Does it work offline and on mobile?

Yes. Once the page has loaded it keeps working without a network connection, and the layout is responsive so it stays usable on phones and tablets.

Ratio Calculator

Solve, simplify, and scale ratios and aspect ratios.

Support

Works Offline

Privacy First

No Login

No API

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

Keyboard shortcuts

Copy the main outputCtrl / ⌘ + Shift + C
Download the resultCtrl / ⌘ + S
Share this toolCtrl / ⌘ + Shift + S
Reset the inputsAlt + R
Open the tool search paletteCtrl / ⌘ + K

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Frequently asked questions

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