Work out the aspect ratio from width and height - reduced, as a decimal and with a proportional target height. Locally, no upload.
No. Everything runs in your browser - your file never leaves your device. How this is verifiable
The aspect ratio describes how the width and height of an image or screen relate to each other - for example 16:9 for widescreen, 4:3 for older monitors, 1:1 for square posts or 3:2 for classic photos. This calculator reduces the ratio of any two dimensions to the smallest whole numbers (via the greatest common divisor), also shows it as a decimal, and on request works out the proportional target height for a desired target width - so you can scale without distortion.
The calculation runs entirely locally in your browser, in pure JavaScript - nothing is uploaded and nothing is stored. Enter the width and height; the calculator works out the reduced ratio and the decimal value. If you also enter a target width, you get the matching height that keeps the ratio exactly. The dimensions are unit-free - you can enter pixels, millimetres or any numbers, the ratio stays the same. Change any input and everything updates instantly.
An honest note: for the reduced ratio the inputs are rounded to whole numbers. If no simple ratio fits (e.g. with odd dimensions like 1234 by 567), the calculator shows the smallest whole-number ratio that fits exactly - which can turn out large. The calculator does not crop anything or add borders; it only computes the dimensions and ratios. To actually crop or scale images, use the matching image tools.
| Input formats | Form inputs (no file) |
|---|---|
| Processing | Locally in your browser (JavaScript) |
| File upload | None |
Limitations: A pure calculation helper: reduces width to height to the smallest whole-number ratio (inputs rounded to whole numbers), shows the decimal value and the proportional target height. Unit-free. It does not crop or scale image files - the image tools do that.
No. The calculation runs entirely locally in the browser (pure JavaScript); nothing is sent or stored.
It is width to height, reduced to the smallest whole numbers. 1920 by 1080 gives 16:9, for example.
Enter the original dimensions and the desired target width - the resulting target height keeps the ratio exactly.
16:9 (widescreen/video), 4:3 (older monitors), 1:1 (square), 3:2 (photos), 21:9 (ultrawide).