Aspect Ratio Calculator
Find the aspect ratio of a size in pixels, such as 1920 × 1080 = 16:9, resize while keeping it, or get the missing side from a ratio like 21:9. How it works
Use the Aspect Ratio Calculator
About the Aspect Ratio Calculator
1920 × 1080 has an aspect ratio of 16:9: divide both sides by their greatest common divisor, 120, to get 16 and 9. To resize and keep the ratio, multiply the height by the new width ÷ the old width, so 1280 wide is 720 high. With only a ratio and one side, type both: 21:9 at 1000 px wide is 1000 × 429.
Common screen and image sizes
| Size (px) | Reduced ratio | Decimal | Closest common ratio |
|---|---|---|---|
| 1280 × 720 | 16:9 | 1.78:1 | Exact |
| 1920 × 1080 | 16:9 | 1.78:1 | Exact |
| 2560 × 1440 | 16:9 | 1.78:1 | Exact |
| 3840 × 2160 | 16:9 | 1.78:1 | Exact |
| 1366 × 768 | 683:384 | 1.78:1 | 16:9, differs by 0.05% |
| 1440 × 900 | 8:5 | 1.60:1 | Same ratio as 16:10 |
| 1920 × 1200 | 8:5 | 1.60:1 | Same ratio as 16:10 |
| 1024 × 768 | 4:3 | 1.33:1 | Exact |
| 1280 × 1024 | 5:4 | 1.25:1 | Exact |
| 3000 × 2000 | 3:2 | 1.50:1 | Exact |
| 2560 × 1080 | 64:27 | 2.37:1 | 21:9, differs by 1.59% |
| 3440 × 1440 | 43:18 | 2.39:1 | 21:9, differs by 2.38% |
| 4096 × 2160 | 256:135 | 1.90:1 | None within 5% |
| 1080 × 1080 | 1:1 | 1.00:1 | Exact |
| 1080 × 1350 | 4:5 | 0.80:1 | Exact |
| 1080 × 1920 | 9:16 | 0.56:1 | Exact |
Ratios as the calculator shows them. Screens sold as 21:9 are rounded: 2560 × 1080 is really 64:27.
Resizing while keeping the ratio
| Original (px) | New side | Result (px) | Before rounding |
|---|---|---|---|
| 1920 × 1080 | Width 1280 | 1280 × 720 | 720 |
| 1920 × 1080 | Width 1000 | 1000 × 563 | 562.5 |
| 1920 × 1080 | Height 1000 | 1778 × 1000 | 1777.78 |
| 1366 × 768 | Width 800 | 800 × 450 | 449.78 |
| 4000 × 3000 | Width 1200 | 1200 × 900 | 900 |
| 1080 × 1920 | Height 1280 | 720 × 1280 | 720 |
The calculated side is rounded to the nearest whole pixel, and a half rounds up.
The other side from a ratio
| Ratio typed | Known side | Result (px) | Before rounding |
|---|---|---|---|
| 21:9 | Width 1000 | 1000 × 429 | 428.57 |
| 16:9 | Height 1080 | 1920 × 1080 | 1920 |
| 2.39:1 | Width 1920 | 1920 × 803 | 803.35 |
| 9:16 | Width 1080 | 1080 × 1920 | 1920 |
| 4:5 | Width 1080 | 1080 × 1350 | 1350 |
| 3:2 | Width 6000 | 6000 × 4000 | 4000 |
The ratio box takes a colon, x, × or slash and up to 4 decimals, and reduces the ratio: 21:9 is shown as 7:3.
Frequently asked questions
- How do I calculate an aspect ratio?
- Divide the width and the height by their greatest common divisor. 1920 and 1080 share 120, giving 16:9; 1080 × 1350 reduces to 4:5.
- Which resolutions are 16:9?
- Any size whose width ÷ height is 16 ÷ 9, about 1.78: 1280 × 720, 1600 × 900, 1920 × 1080, 2560 × 1440 and 3840 × 2160 all reduce to 16:9.
- What is the height of a 16:9 image 1000 pixels wide?
- 562.5 pixels, which the calculator rounds to 563 (a half rounds up) while showing 562.5 as the value before rounding. Type 16:9 in the ratio box and 1000 as the known width, or enter 1920 × 1080 and a new width of 1000.
- Is 1366 × 768 a 16:9 resolution?
- Not exactly. It reduces to 683:384 (1.78:1), which differs from 16:9 by 0.05%, so the calculator names 16:9 as the closest common ratio.
- What is the difference between 16:10 and 16:9?
- 16:10 (1.60:1) is taller than 16:9 (1.78:1). 1920 × 1200 is 16:10, which the calculator reduces to 8:5, and 1920 × 1080 is 16:9: the same width with 120 fewer rows.
- How do I change an image from 4:3 to 16:9?
- You have to cut part of it away, because resizing here always keeps the original shape. A 4000 × 3000 photo becomes 16:9 at 4000 × 2250 by trimming 750 rows; enter 4000 and 2250 here to check the result reduces to 16:9. To make the cut on the image itself, use the Image Cropper and pick its 16:9 frame.
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