Aspect Ratio Calculator
Enter a size to get its ratio, or a ratio and one side to get the other, answered in a sentence.
Resize keeping the ratio: enter a new width or a new height.
Enter the width to get the height, or the height to get the width.
Enter a width and height to see the ratio.
Your input is processed in your browser and is not uploaded.
How to use it
- Choose "I have a size" and enter a width and height to get the ratio.
- Enter a new width or a new height to resize with the same proportions.
- Or choose "I have a ratio", pick a preset such as 16:9, and enter a width or a height.
Example
Input: 1920 × 1080, new width 1280
Result: Your aspect ratio is 16:9. At 1280 wide the matching height is 720.
How we calculated this
The ratio is the width and height divided by their greatest common divisor: 1920 and 1080 share a divisor of 120, so 1920:1080 reduces to 16:9.
To resize, the new height is the new width × height ÷ width, and the new width is the new height × width ÷ height, so the proportions stay the same. 1280 × 1080 ÷ 1920 = 720.
Some sizes are not an exact standard ratio. 1366 × 768 reduces to 683:384, which is within a fraction of a percent of 16:9, so the page names the closest standard ratio when one is within 1%.
Assumptions
- Sizes can have up to three decimal places.
- Results that are not whole numbers are shown exactly and also rounded to the nearest whole pixel.
- Standard ratios considered: 16:9, 9:16, 4:3, 3:4, 3:2, 2:3, 1:1, 21:9, 16:10, 5:4 and 4:5.
Questions
Why is my ratio something odd like 683:384?
That is the exact ratio of the size you entered. When it is very close to a standard ratio, the page also tells you which one.
What is the difference between 16:10 and 8:5?
Nothing: they are the same ratio. The page shows the commonly used name and notes the reduced form.