Aspect Ratio Calculator
Width and height reduce by their greatest common divisor. You also get a decimal ratio, landscape or portrait, and optional scale to a target side. This is not crop advice.
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How to find an aspect ratio
- Enter pixel or length width and height. Units cancel as long as both sides match.
- Read the reduced ratio, the decimal width over height, and orientation.
- Optional: type a target width or target height to scale the other side.
- The page does not suggest a crop. Copy the rows. Nothing is uploaded.
Aspect ratio
Width to height after GCD reduction
| Reduced ratio | width/GCD : height/GCD |
|---|---|
| Decimal | width / height |
| Orientation | Landscape, portrait, or square |
| Scale to width | height = targetW × (height / width) |
| Scale to height | width = targetH × (width / height) |
| Common example | 1920×1080 reduces toward 16:9 |
How the ratio is reduced
The greatest common divisor of rounded width and height divides both sides. 1920 and 1080 share 120, so the ratio is 16:9. Decimal is width divided by height. Equal sides report square.
16:9, pixels, and scale
16:9, 4:3, and 1:1 are named ratios people search. This page accepts any positive pair. Rectangle area and perimeter live on the rectangle calculator. Palette jobs sit on the color palette generator.
Not crop or encode advice
Keeping a ratio is not the same as choosing a crop box, a codec, or a safe-area overlay. You scale one side. You do not receive composition guidance.
Use cases
Checking a 1920×1080 frame, fitting a still to a 1280-wide slot, or confirming a square export. Print DPI is not computed.
Limits
Width and height must be greater than 0. GCD uses rounded integers, so tiny fractional pixels can change the reduced pair. CZNull does not receive the numbers.