Aspect Ratio Calculator
Leave either the width or the height blank and the matching value is calculated for your ratio.
How to use the Aspect Ratio Calculator
- Enter the Original width and Original height of the image or video you are resizing.
- Enter the New width you are aiming for, then press Calculate.
- The matching New height comes back as a whole number, keeping the proportions.
Getting a width out of a height
The calculation runs from width to height, but a ratio does not mind which side is which. Swap the two original figures, put your target height into New width, and the answer is the width you need.
Whole pixels and even numbers
The answer is rounded to the nearest whole pixel, so the ratio can sit a hair off the original: 1920 by 1080 at a width of 1000 gives 562.5, returned as 563. Nudge an odd result by one for video.
| Ratio | Typical size | Width / height |
|---|---|---|
| 16:9 | 1920 x 1080 | 1.778 |
| 4:3 | 1024 x 768 | 1.333 |
| 21:9 | 3440 x 1440 | 2.389 |
Frequently asked questions
Can I work from the height instead?
Yes, by swapping the inputs: original height into Original width, original width into Original height, and the height you want into New width.
Does it work for video?
Yes, for any ratio including 16:9, 4:3, 21:9 and 1:1.
What height goes with a width of 1280 for a 16:9 video?
720 pixels. Enter 1920 and 1080 as the originals and 1280 as the new width, and you get the standard 720p frame.
Can I leave one of the boxes empty?
No. All three boxes are required, and an empty or non-numeric one is highlighted instead of calculated.
Does it tell me what my ratio is called?
No, it returns the new height only. To name a ratio, divide width by height: 1.78 is 16:9 and 1.33 is 4:3.