How to use the aspect ratio calculator
- Pick a ratio with a preset button, or type your own, such as 21:9.
- Type a width or a height. The other side is calculated to keep the ratio.
- To find the ratio of a size you already have, untick “Keep the ratio” and enter both numbers.
Common aspect ratios and resolutions
| Ratio | Used for | Common sizes (px) |
|---|---|---|
| 16:9 | YouTube, TV, thumbnails | 1280 × 720, 1920 × 1080, 3840 × 2160 |
| 9:16 | TikTok, Reels, Shorts, Stories | 1080 × 1920 |
| 4:5 | Instagram and Facebook portrait posts | 1080 × 1350 |
| 1:1 | Square posts, profile photos | 1080 × 1080 |
| 3:4 | Instagram profile grid, tablets | 1080 × 1440 |
| 4:3 | Older video, presentations, iPad | 1024 × 768, 1440 × 1080 |
| 2:3 | Pinterest pins, photo prints | 1000 × 1500 |
| 21:9 | Ultrawide, cinematic video | 2560 × 1080, 3440 × 1440 |
| 1.91:1 | Link previews, landscape posts | 1200 × 628 |
Tips for choosing a ratio
- Film in the ratio you post in. Cropping 16:9 to 9:16 throws away about two thirds of the frame.
- Video sizes should be even numbers, since most video encoders require it.
- Shoot vertical content with the safe zone in mind, and crop finished images with the image resizer.
Last reviewed October 2026.
Frequently asked questions
How do you calculate an aspect ratio?
Divide the width and height by their greatest common divisor. For 1920 × 1080 the divisor is 120, which gives 16:9. The calculator does this for you and also shows the ratio as a decimal, such as 1.78.
How do I find the height for a 16:9 video?
Multiply the width by 9 and divide by 16. For a width of 1280 pixels the height is 720. Enter the width, choose 16:9 and the calculator fills in the height.
What aspect ratio is best for TikTok, Reels and Shorts?
9:16 vertical, at 1080 × 1920 pixels. It fills a phone screen with no bars.
What aspect ratio should I use for Instagram posts?
4:5 portrait, 1080 × 1350 pixels, takes up the most space in the feed. 1:1 square (1080 × 1080) also works everywhere.
Why does my result show a ratio like 683:384?
Some screen sizes, such as 1366 × 768, don’t reduce to a neat ratio. The calculator also shows the closest standard ratio, in this case 16:9.
Can I resize an image to a new ratio here?
This page calculates sizes. To actually crop an image to a ratio, use the social media image resizer.