Aspect Ratio Calculator
Enter a width and height to get the aspect ratio, like 16:9. Or switch to scale mode: lock the shape, change one side, and read the other.
Enter a width and height to see the ratio.
Find ratio reduces width and height by their greatest common divisor. Scale size keeps that shape: new height is new width times original height divided by original width.
How It Works
In ratio mode, type a width and height. The tool simplifies them to their lowest whole numbers and names common ratios.
It does this with the greatest common divisor. Dividing both sides by it gives the simplest form of the ratio.
In scale mode, enter the original width and height, then a new width. The tool gives the new height that keeps the same shape.
The Formula
For 1920 by 1080, the greatest common divisor is 120.
Divide both: 1920 ÷ 120 is 16, and 1080 ÷ 120 is 9, giving 16:9.
To scale, new height = new width × original height ÷ original width, which holds the ratio steady.
Worked Example
Start with a 1920 by 1080 frame and find its ratio.
The greatest common divisor of 1920 and 1080 is 120.
Divide both by 120 to get 16:9, the standard widescreen ratio.
Common Uses
- Reading the ratio of a screen, photo, or video frame.
- Resizing an image without squashing or stretching it.
- Checking whether two sizes share the same shape.
- Setting a crop to a target ratio like 4:3 or 1:1.