Aspect Ratio Calculator
Enter a width and height to get the simplified ratio (1920 × 1080 → 16:9), or enter a ratio and one new dimension to get the other.
Find the aspect ratio
Resize and keep the ratio
How the ratio is found
The aspect ratio is width : height reduced to lowest terms. Divide both by their greatest common divisor: for 1920 × 1080 the GCD is 120, so the ratio is 16 : 9. Some sizes do not reduce neatly — 1366 × 768 is exactly 683 : 384 — so the calculator also names the closest common ratio (16 : 9, within 0.05%).
Resizing
new height = new width × ratio height ÷ ratio width
new width = new height × ratio width ÷ ratio height
Scale a 16:9 video to 1,280 pixels wide
- 1,280 × 9 ÷ 16 = 720
1280 × 720
Common aspect ratios
| Ratio | Decimal | Typical use | Example sizes |
|---|---|---|---|
| 1:1 | 1 | Square social posts | 1080 × 1080 |
| 4:3 | 1.333 | Older TVs and monitors, many tablets and compact cameras | 1024 × 768, 1600 × 1200 |
| 3:2 | 1.5 | 35 mm film and most DSLR photos | 6000 × 4000 |
| 16:10 | 1.6 | Many laptops and monitors | 1920 × 1200, 2560 × 1600 |
| 16:9 | 1.778 | HD and 4K video, TVs, most monitors | 1280 × 720, 1920 × 1080, 3840 × 2160 |
| 21:9 | ≈ 2.37 | “Ultrawide” monitors (usually 64:27 exactly) | 2560 × 1080, 3440 × 1440 |
| 9:16 | 0.5625 | Vertical phone video and stories | 1080 × 1920 |