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Aspect Ratio Calculator

Solve any width or height.

An aspect ratio is width to height, written like 16:9. This calculator does two jobs. It simplifies a resolution to its ratio, so 1920x1080 becomes 16:9, and it solves for the width or height that keeps a ratio you pick. Enter a ratio and one dimension, get the other. Everything runs in your browser, nothing is uploaded.

How it works

Two small pieces of arithmetic:

  • Simplify divides both numbers by their greatest common divisor. 1920 and 1080 share 120, so 1920:1080 reduces to 16:9.
  • Height = width x ratio height / ratio width.
  • Width = height x ratio width / ratio height.

Worked examples

Resolution Aspect ratio
1,920 x 1,080 16:9
1,280 x 720 16:9
1,080 x 1,080 1:1
1,620 x 1,080 3:2
2,560 x 1,080 64:27

The last row is the giveaway: 2560x1080 ultrawide monitors are sold as 21:9, but the exact reduced ratio is 64:27. The calculator shows the real number, not the marketing name.

Common ratios

Ratio 16:9

Questions people ask

What is an aspect ratio?

An aspect ratio is the proportional relationship between width and height, written as two numbers separated by a colon, like 16:9. It describes shape, not size: a 1280x720 image and a 1920x1080 image are both 16:9, so they look identical in proportion and only differ in pixel count. You get the ratio by dividing both dimensions by their greatest common divisor.

How do I calculate 16:9 dimensions?

Multiply the width by 9 and divide by 16 to get the matching height, or multiply the height by 16 and divide by 9 to get the width. For example, a width of 1920 gives 1920 x 9 / 16 = 1080. A height of 720 gives 720 x 16 / 9 = 1280. The calculator does this for any ratio you enter.

What resolution is 16:9?

Any resolution where width divided by height equals 16/9. The common ones are 720p (1280x720), 1080p or Full HD (1920x1080), 1440p or QHD (2560x1440), and 4K UHD (3840x2160). Each is exactly 16:9, which is why video scales cleanly between them.