Aspect Ratio Calculator
Enter the width and height of an image or video to get its simplified aspect ratio, or pick a ratio and one side to find the other (for example, the height of a 16:9 frame that is 1280px wide). Common presets and a resolution list for each ratio are included. To actually scale an image, use the Image Resizer; to see your screen size, try the Viewport Checker. Everything runs in your browser and nothing is sent to a server.
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Find the ratio from width and height
- Aspect ratio (simplified)
- Ratio value (width / height)
- Closest common ratio
Find a missing side from a ratio
Resolution list
| Width | Height |
|---|
Notes
- When the result is not a whole number, it is rounded to the nearest integer. For real images and video you may need further adjustment, such as using even numbers.
- Decimal widths and heights are converted to integers using up to 6 decimal places before simplifying.
- "Closest common ratio" is the preset whose ratio value is nearest to yours; it does not mean the size is an official standard.
- Sizes such as 1366×768 do not reduce to small numbers, so they are shown as close to 16:9.
Glossary
Aspect ratio
The proportion between the width and height of an image or screen. 1920×1080 is 16:9. It is usually written as width:height.
Simplifying
Dividing width and height by their greatest common divisor to get the smallest whole-number ratio. 1920 and 1080 share a divisor of 120, giving 16:9.
Resolution
The number of pixels in an image or display (width × height). One aspect ratio has many resolutions, e.g. 1280×720, 1920×1080 and 3840×2160 for 16:9.
FAQ
What is the aspect ratio of 1920×1080?
It is 16:9. Dividing both sides by their greatest common divisor (120) gives 16:9. Enter a width and height and the tool shows the simplified ratio.
What happens when the result is not a whole number?
The result is rounded to the nearest integer and the exact value is shown alongside it. Some video codecs need even dimensions, so adjust the result for your use case.
Why is 1366×768 not shown as 16:9?
Strictly, 1366×768 reduces to 683:384, which is slightly different from 16:9 (1.7778). The tool shows the exact simplified ratio and also lists 16:9 as the closest common ratio.
Can I calculate portrait ratios such as 9:16?
Yes. The presets include portrait ratios such as 9:16, 3:4 and 2:3, and the custom option accepts any ratio you type.
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