Aspect Ratio Resize Calculator
Enter the original width and height, then change either the new width or the new height. The calculator scales the other dimension to keep the same proportions and shows the simplified ratio.
How to resize keeping the aspect ratio
- Enter the original width and height in pixels.
- Type a new width or a new height, not both.
- Read the matching dimension and the simplified aspect ratio.
Examples
Scale down a 1080p frame
1920x1080, new width 1280
1280x720 (16:9)
Solve width from a new height
1920x1080, new height 480
853x480 (16:9)
Frequently asked questions
How does proportional resizing work?
The new dimension is scaled by the same factor as the one you set. For a new width, the height becomes the new width times the original height divided by the original width, rounded to whole pixels.
Why round to whole pixels?
Pixels are discrete, so a fractional result is rounded to the nearest whole number. That can shift the ratio by a tiny amount, but it keeps the output to a valid integer size.
How is the simplified ratio found?
The tool divides the original width and height by their greatest common divisor. For 1920 by 1080 that divisor is 120, which simplifies to 16:9.
Can I use this for portrait video?
Yes. Enter a taller-than-wide source, such as 1080 by 1920, and the calculator returns the 9:16 ratio and scales correctly.
Does it stretch or distort the image?
No. By scaling both dimensions by the same factor it preserves proportions, so nothing is stretched or squashed.
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