What is an aspect ratio?
An aspect ratio describes the shape of an image, a video or a screen: how wide it is compared with how tall. It is written as two numbers with a colon, width first. 16:9 means 16 units of width for every 9 units of height.
The ratio says nothing about the size. 1280 × 720 and 3840 × 2160 are both 16:9: the same shape, one nine times the area of the other.
How the calculation works
To find a missing side, multiply the side you know by the ratio:
- Height = width × ratio height ÷ ratio width
- Width = height × ratio width ÷ ratio height
For 16:9 and a width of 1280 px: 1280 × 9 ÷ 16 = 720 px. To find the ratio of a size, divide both sides by their greatest common divisor. 1920 and 1080 are both divisible by 120, which leaves 16 and 9.
Common aspect ratios
| Ratio | Decimal | Where you see it | Example size |
|---|---|---|---|
| 16:9 | 1.78:1 | HD and 4K video, most monitors and TVs | 1920 × 1080 |
| 4:3 | 1.33:1 | Older screens, many tablets, presentation slides | 1024 × 768 |
| 3:2 | 1.5:1 | Photos from most cameras | 3000 × 2000 |
| 1:1 | 1:1 | Profile pictures, square posts | 1080 × 1080 |
| 4:5 | 0.8:1 | Portrait posts on social media | 1080 × 1350 |
| 9:16 | 0.56:1 | Stories and vertical video | 1080 × 1920 |
| 21:9 | 2.33:1 | Ultrawide screens (many are closer to 2.37:1) | 2520 × 1080 |
Resize or crop?
Resizing keeps the ratio: the whole picture stays, only larger or smaller. When the place you need the picture for has a different ratio, something has to give. You can crop, which cuts part of the picture off, or pad, which adds bars at the sides. Stretching a picture to fit changes its ratio and distorts everything in it, faces first.
The ratio of a profile picture
Profile pictures are square files, 1:1, even where they are shown as a circle. If your photo is 4:5 or 3:2, crop it to a square with your face in the middle before you upload it.