Aspect Ratio Calculator
Find the aspect ratio of any width and height (like 1920×1080 = 16:9), and calculate a new width or height that keeps the same proportions.
How to use
- 1Enter the original width and height.
- 2Enter a new width (or height) to get the matching other side.
How it's calculated
Ratio = width ÷ gcd : height ÷ gcd. New height = new width × original height ÷ original width.
Frequently asked questions
What aspect ratio is 1920×1080?
16:9 — the standard for HD and 4K video, YouTube and most monitors.
What ratio should I use for Instagram?
4:5 (1080×1350) for portrait feed posts, 1:1 for square and 9:16 for Stories and Reels.
Why does my ratio look odd, like 683:384?
Some resolutions (like 1366×768) aren't exact common ratios. The decimal value (1.78) shows it's approximately 16:9.