Aspect Ratio Calculator
Resize anything without stretching it. Enter the original width and height (or pick a ratio like 16:9), then type a new width or height and the calculator fills in the other. It also simplifies the ratio, gives its decimal value, and lists standard sizes in that ratio.
- Runs in your browser
- Nothing is uploaded
- Free, no sign-up
Standard sizes in this ratio
How to use the aspect ratio calculator
- Enter the original width and height, such as an image of 1920 x 1080, or press a ratio button like 16:9.
- Type the new width in W2 and the new height appears in H2. Or type the new height in H2 and the width appears in W2.
- Keep Round to whole pixels on for image and video sizes; turn it off for exact values such as print sizes.
- Read the simplified ratio and decimal value, and pick a standard size from the list if you need one.
What the results mean
The calculator keeps the shape the same: H2 = W2 x H1 / W1 and W2 = H2 x W1 / H1. Resizing 1920 x 1080 to a width of 1280 gives 1280 x 720; to a height of 1440 gives 2560 x 1440.
The aspect ratio is the original size divided by the greatest common divisor of width and height: 1920 x 1080 divides by 120 to give 16:9. The decimal is width divided by height, the form used in cinema (2.39:1) and in CSS (aspect-ratio: 16 / 9). The note under the numbers names the closest standard ratio, which helps with sizes that do not reduce neatly, like 1366 x 768.
Common aspect ratios and where they are used
| Ratio | Sizes | Used for |
|---|---|---|
| 16:9 | 1280 x 720, 1920 x 1080, 3840 x 2160 | YouTube, TVs, most monitors, presentations |
| 9:16 | 1080 x 1920 | TikTok, Instagram Reels and Stories, YouTube Shorts |
| 4:5 | 1080 x 1350 | Instagram portrait posts |
| 1:1 | 1080 x 1080 | Square posts, profile pictures |
| 4:3 | 1024 x 768, 1600 x 1200 | Old TVs, iPad, many compact cameras |
| 3:2 | 6000 x 4000 | 35 mm film, most DSLR and mirrorless photos, 6 x 4 inch prints |
| 16:10 | 1920 x 1200, 2560 x 1600 | Laptops and work monitors |
| 21:9 | 2560 x 1080, 3440 x 1440 | Ultrawide monitors, cinema-style video |
Resizing images and video without distortion
If you change the width and height by different amounts, the picture stretches. Keep the ratio and only change one side, as this calculator does. When the target has a different ratio, such as a 16:9 video for a 9:16 phone format, you have to choose: crop the sides (fills the screen, loses part of the picture) or letterbox (shows everything with bars). Most editors call these "fill" and "fit". For a picture of your own screen's ratio, the screen ratio page shows it, and screen resolution gives the pixel size.
Common problems and fixes
The new height has decimals
Not every width gives a whole-number height in a ratio. Turn on "Round to whole pixels", or choose a width from the standard sizes list, which divide evenly.
My video size must be an even number
Many video encoders need even widths and heights. Round the result to the nearest even number; the change in shape is too small to see.
The ratio shows a long decimal
You entered a size with decimals. Use whole pixel sizes to get a simplified ratio such as 16:9.
Frequently asked questions
How do I calculate the aspect ratio?
What height is 16:9 at 1280 wide?
What is the aspect ratio of 1080 x 1350?
Is 1920 x 1080 the same as 16:9?
What is the formula for the new height?
Can I use this for print sizes?
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