Aspect Ratio Calculator
Find the aspect ratio of an image, video or screen, and calculate a new width or height that keeps the same proportions when resizing.
How to use the Aspect Ratio Calculator
- Enter the original width and height.
- Optionally enter a new width (or height).
- Read the simplified ratio and the matching dimension.
How it works
The aspect ratio is width : height reduced by their greatest common divisor: 1920 × 1080 → divide both by 120 → 16:9. To resize without distortion, keep the ratio: new height = new width × height ÷ width. Scaling 1920 × 1080 to a width of 1280 gives a height of 720.
Common aspect ratios
| Ratio | Example resolution | Used for |
|---|---|---|
| 16:9 | 1920 × 1080 | HD TV, YouTube, monitors |
| 4:3 | 1024 × 768 | Older TVs, iPad |
| 3:2 | 6000 × 4000 | DSLR photos |
| 21:9 | 2560 × 1080 | Ultrawide monitors, cinema |
| 1:1 | 1080 × 1080 | Instagram posts |
| 9:16 | 1080 × 1920 | Stories, Reels, TikTok |
Frequently asked questions
What aspect ratio is 1920×1080?
16:9.
What is the height of a 16:9 image 1280 wide?
720 pixels.
What aspect ratio is 4K?
Consumer 4K UHD (3840 × 2160) is 16:9.
What ratio do phones record vertical video in?
Usually 9:16, the same as 16:9 turned on its side.
How do I crop a photo to 4:5 for Instagram?
Keep the width and set the height to width × 5 ÷ 4. A 1080-pixel-wide image becomes 1080 × 1350.
Does changing the aspect ratio distort an image?
Stretching it does. To keep proportions, either crop to the new ratio or add bars (letterboxing) instead of stretching.