Aspect Ratio Calculator
Width
1920
Height
1080
Decimal Ratio
1.7778
How it works
The aspect ratio calculator finds a missing width or height so an image, video or screen keeps the right proportions. Pick a preset ratio (16:9, 4:3, 21:9, 1:1, 4:5 or 9:16) or enter a custom one, then type either a width or a height. The other dimension is filled in automatically.
The math is a simple proportion. The calculator divides the ratio's width by its height to get the decimal ratio, such as 16 / 9 = 1.7778. If you enter a width, the height is width / decimal ratio. If you enter a height, the width is height x decimal ratio. For example, 1920 pixels wide at 16:9 gives a height of 1080.
Results are rounded to two decimal places, and the decimal ratio to four. If you get a fraction of a pixel, round to the nearest whole number, or pick a size that divides evenly by the ratio. Common uses include sizing video for widescreen (16:9), vertical video and stories (9:16), square posts (1:1) and portrait social images (4:5).
Frequently asked questions
What is an aspect ratio?+
An aspect ratio describes the shape of a rectangle as width compared with height, such as 16:9. Any size with the same ratio has the same shape, whether it's 1280 x 720 or 3840 x 2160.
How do I calculate height from width and aspect ratio?+
Divide the width by the ratio's width and multiply by its height. For 16:9 at 1280 pixels wide, the height is 1280 / 16 x 9 = 720.
What resolution is 16:9?+
Common 16:9 resolutions include 1280 x 720 (HD), 1920 x 1080 (Full HD), 2560 x 1440 (QHD) and 3840 x 2160 (4K UHD).
What aspect ratio should I use for social media?+
Vertical video and stories usually use 9:16, square posts use 1:1, and portrait feed images often use 4:5. Platforms change their recommendations from time to time, so check their current guidelines.