Aspect Ratio Calculator
Calculate the aspect ratio of any image or video, or scale dimensions while maintaining a fixed ratio.
Runs in your browser Your input never leaves your device.
About this tool
Enter the width and height of an image or video in pixels to see its aspect ratio reduced to the smallest whole numbers, such as 16:9 or 4:3. The tool rounds each side to the nearest whole number, then divides both by their greatest common divisor. If you also enter a new width, it returns the height that keeps the same proportions, rounded to two decimal places. It works for any dimensions, so it is useful for resizing a photo, planning a video export or setting an embed size. Only a new width is supported; there is no field for entering a new height. Everything is calculated in your browser as you type.
How to use it
- Enter the current width.
- Enter the current height.
- Read the simplified ratio.
- Optionally enter a new width to get the height that preserves the ratio.
Example
Width 1920, Height 1080, New width 1280
Aspect ratio: 16:9 Height for width 1280: 720
Common problems
- The ratio looks odd, like 683:384
- Ratios are only reduced by the exact greatest common divisor. 1366x768 is close to 16:9 but not exactly, so it reduces to 683:384.
- The new height has decimals
- The height is not rounded to whole pixels, only to two decimals. Round it yourself to a whole number, which slightly changes the ratio.
- No result is shown
- Both width and height must be greater than zero. Decimal inputs are rounded to whole numbers first.