DigiKitAspect Ratio Calculator
Enter a width and height to get the simplified aspect ratio, and enter a new width or height to find the matching dimension.
How an aspect ratio is found
An aspect ratio describes the relationship between width and height. To find it, divide both numbers by their greatest common divisor. For 1920 × 1080 the divisor is 120, giving 16:9. The decimal ratio (width ÷ height) is 1.7778.
To resize while keeping the proportions, use new height = new width × height ÷ width, or new width = new height × width ÷ height.
Worked examples
- 1920 × 1080 is 16:9. Scaled to a width of 1280, the height is 1280 × 1080 ÷ 1920 = 720.
- 1080 × 1350 simplifies to 4:5, a portrait ratio with a decimal ratio of 0.8.
- 1000 × 1000 is 1:1, a square. A height of 250 means a width of 250.
Common aspect ratios
| Ratio | Typical use | Example size |
|---|---|---|
| 16:9 | Widescreen video and most monitors | 1280 × 720, 1920 × 1080, 3840 × 2160 |
| 9:16 | Vertical video | 1080 × 1920 |
| 4:3 | Older TVs and many tablets | 1024 × 768 |
| 3:2 | 35 mm film and many cameras | 1500 × 1000 |
| 1:1 | Square | 1080 × 1080 |
| 21:9 | Ultrawide monitors (marketed as 21:9; exact sizes vary) | 2560 × 1080 simplifies to 64:27 |
How to use the calculator
- Enter the current width and height in pixels, or any other units.
- To resize, enter either a new width or a new height.
- Press Run to see the simplified ratio, the decimal ratio, the orientation and the matching dimension.
16:9 sizes at different resolutions
| Width × height | Ratio |
|---|---|
| 640 × 360 | 16:9 |
| 1280 × 720 | 16:9 |
| 1920 × 1080 | 16:9 |
| 2560 × 1440 | 16:9 |
| 3840 × 2160 | 16:9 |
Doubling both dimensions keeps the ratio, so 960 × 540 is also 16:9. When you reduce an image for the web, change both dimensions by the same factor, or use the calculator to find the second dimension.
Things to keep in mind
- Use whole numbers for width and height to see the simplified ratio. Decimals are accepted but then only the decimal ratio is shown.
- Resized dimensions are rounded to two decimals. Round to a whole pixel yourself where needed.
- Changing only the width or only the height of an image stretches it. Scale both with the same ratio instead.
- Some sizes are not exactly a standard ratio. 1366 × 768, for instance, is very close to 16:9 but simplifies to 683:384.
Frequently asked questions
How do I find the aspect ratio of an image?
Divide the width and the height by their greatest common divisor. The calculator does this for you: enter both values and read the ratio.
How do I resize without distorting?
Enter the new width (or new height) and use the matching height (or width) the calculator returns.
What is the aspect ratio of 1920 × 1080?
16:9. The same applies to 1280 × 720 and 3840 × 2160.
Why does my size not match a standard ratio?
Some screens and cameras use sizes that are only close to a standard ratio. The calculator shows the exact simplified ratio.
Is my data stored?
No. The calculation runs in your browser.