Aspect Ratio Calculator
Work out a missing width or height that keeps a given aspect ratio.
Resizing without distortion
When you resize something and want to keep its proportions, you set one dimension and need the other to match the aspect ratio. This calculates that missing dimension, so a video, image or box scales cleanly to a new width or height without stretching or squashing.
Enter the ratio and one dimension, and get the other.
Why proportions matter more than size
Getting the aspect ratio right is what keeps content looking correct at any size — the same proportions scale into each other perfectly, while a mismatch is exactly what causes stretched faces and squashed logos. Common ratios like 16:9 for video and 4:3 for older screens crop up constantly, and knowing the matching dimension for a target width lets you fit content into a space without distortion or the black bars that appear when the ratio is wrong.
Frequently asked questions
What does it calculate?
The missing width or height that preserves a given aspect ratio, so content scales without distortion.
Why does keeping the ratio matter?
Because matching proportions scale cleanly, while a mismatch stretches or squashes the content or forces black bars.
Is anything uploaded?
No. The calculation happens in your browser.