Aspect ratio calculator
Enter a width and height to get the simplified ratio. Then type a new width or height to get the matching other side, with no stretching.
Type either one. The other keeps the same shape.
What happens when ratios don’t match
A ratio is just shape. Two images with the same ratio scale into each other perfectly; different ratios force a choice between cropping, bars and distortion.
The formula
An aspect ratio is width : height reduced to the smallest whole numbers. Divide both by their greatest common divisor (GCD): 1920 and 1080 share 120, so 1920 × 1080 is 16:9. Some sizes don’t reduce neatly. 1200 × 628 is 300:157, so people call it 1.91:1 (1200 ÷ 628).
To resize without distortion, keep the ratio: new height = new width × old height ÷ old width. For a 4000 × 3000 photo resized to 1200 wide: 1200 × 3000 ÷ 4000 = 900.
If the target has a different ratio, you have to crop. Crop the image to the target shape first, then scale it.
Common aspect ratios
| Ratio | Used for | Typical pixels |
|---|---|---|
| 1:1 | Square posts, profile photos, product photos | 1080 × 1080, 2048 × 2048 |
| 4:5 | Instagram / Facebook portrait posts | 1080 × 1350 |
| 3:4 | Instagram profile grid, many phone photos | 1080 × 1440 |
| 2:3 | Pinterest pins, 35 mm prints (4×6 in) | 1000 × 1500 |
| 4:3 | Classic cameras, iPad, Etsy listings | 1600 × 1200, 3000 × 2250 |
| 3:2 | DSLR and mirrorless photos | 6000 × 4000 |
| 16:10 | Laptop screens | 1920 × 1200, 2560 × 1600 |
| 16:9 | YouTube, TV, monitors, slides | 1280 × 720, 1920 × 1080, 3840 × 2160 |
| 1.91:1 | Link previews, Facebook / LinkedIn landscape posts | 1200 × 628 |
| 21:9 | Ultrawide monitors, cinema | 2560 × 1080, 3440 × 1440 |
| 3:1 | X (Twitter) header | 1500 × 500 |
| 4:1 | LinkedIn banner | 1584 × 396 |
| 9:16 | Stories, Reels, TikTok, Shorts | 1080 × 1920 |
Questions
How do I calculate an aspect ratio?
Divide width and height by their greatest common divisor. 1920 × 1080: the GCD is 120, so the ratio is 16:9.
What is 16:9 in pixels?
Common 16:9 sizes are 1280 × 720 (HD), 1920 × 1080 (Full HD), 2560 × 1440 (QHD) and 3840 × 2160 (4K UHD).
What is a 4:5 aspect ratio?
A portrait shape 4 units wide by 5 tall, such as 1080 × 1350. It is the tallest shape Instagram’s feed allows.
How do I resize but keep the aspect ratio?
Enter the new width and the calculator gives the height (or the other way round). New height = new width × original height ÷ original width.
What aspect ratio is 1080 × 1920?
9:16, vertical video and stories.