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Aspect Ratio Calculator
Calculate a new width or height while keeping the original aspect ratio.
Overview
Calculates a new width or height while preserving the original aspect ratio.
Useful when resizing an image, video, or banner and you need the other dimension without distorting the ratio.
Also displays a simplified aspect ratio, such as 16:9, based on the original width and height.
Usage
- 1
Enter the pre-resize values into "Original width" and "Original height".
- 2
Under "Field to specify", choose whether to specify the new width or height.
- 3
Enter the new width or height you want into "Value".
- 4
Click "Calculate" to see the other dimension and the aspect ratio.
Example
Input
Original: 1920x1080, new width: 1280
Output
New height: 720, ratio: 16:9
Use Cases
Calculating the height when resizing an image to a specific width in a responsive design
Finding dimensions that preserve the aspect ratio when exporting a banner or thumbnail at a different size
Checking a value that keeps the aspect ratio intact when changing a video's resolution
FAQ
How is the aspect ratio simplified?
If the original width and height are integers, they are divided by their greatest common divisor and shown as a form like "16:9". If either contains a decimal, the ratio is shown as entered, without simplification.
Can I specify both width and height at the same time?
No. Enter only the value for the field you chose under "Field to specify"; the other value is calculated automatically from the original ratio.
Notes
Results are not rounded to whole numbers. Resizing 1920×1080 to a width of 1000 gives a height of 562.5, so round the value yourself if you need a pixel count (rounding shifts the ratio slightly).
The displayed ratio is the original width and height reduced by their greatest common divisor. For example, 1366×768 is not exactly 16:9, so it is shown as "683:384".
Values that don't divide evenly are shown as approximations with 10 significant digits.
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