Which field updates automatically?

Whichever one you did not edit last — edit the width and the height is computed, and vice versa.

What ratios are preset?

16:9, 4:3, 1:1, 3:2, 21:9 and vertical 9:16.

Yes, dimensions can be decimal and results are shown to two places.

Aspect Ratio Calculator

Scale width and height together at any ratio, with common presets.

aspect.exe

Ratio presets

Ratio widthRatio heightPixel widthPixel height

1920 × 1080

ratio 16:9 · entered dimensions simplify to 16:9

How to use Aspect Ratio Calculator

01Pick a preset ratio or enter your own ratio width and height.
02Type a pixel width or height — the other dimension fills in automatically.
03The preview box and simplified ratio update as you type.

About Aspect Ratio Calculator

An aspect ratio is just a fraction: 16:9 means sixteen units of width for every nine of height. To scale one dimension you multiply by the ratio's other side, so a 1920-wide 16:9 image is 1920 × 9 ÷ 16 = 1080 tall.

The tool also simplifies the dimensions you enter to their smallest whole-number ratio using the greatest common divisor — 1920×1080 reduces to 16:9, while 1366×768 reduces to 683:384, which is why that laptop resolution never matches a clean preset.

Frequently asked questions

Which field updates automatically?: Whichever one you did not edit last — edit the width and the height is computed, and vice versa.
What ratios are preset?: 16:9, 4:3, 1:1, 3:2, 21:9 and vertical 9:16.
Can I use decimals?: Yes, dimensions can be decimal and results are shown to two places.