Aspect Ratio Resizer
Scale an image or video to a new width or height while keeping its original proportions.
How it works
Keeping the aspect ratio means the new size has the same shape as the original — no stretching or squashing. The trick is that width and height have to change by the same factor.
Enter the original width and height, pick whether you're setting a new width or a new height, and type that value. The tool multiplies through the original ratio to find the other dimension. Scale a 1920×1080 image down to 1280 wide and the height lands at 720.
It also simplifies the original into a clean ratio like 16:9 by dividing both sides by their greatest common divisor, so you can see at a glance what shape you're working with.
Frequently asked questions
What is an aspect ratio?
It's the proportional relationship between width and height, written like 16:9 or 4:3. It describes the shape of a frame regardless of its actual pixel size, so a 1280×720 and a 1920×1080 image share the same 16:9 ratio.
Why do I get a fractional pixel result?
Ratios don't always divide into whole numbers. The calculator shows the exact figure; when you actually export, round to the nearest whole pixel — a fraction of a pixel makes no visible difference.
Can I use this for video?
Yes. The math is identical for any rectangle — photos, video frames, banners, or crop regions. Just keep width and height in the same units and you'll preserve the shape.