Aspect Ratio Calculator
Enter the original size and one new dimension — get the other without breaking the ratio.
Where aspect ratios matter
Resizing a video thumbnail, fitting an image into a slide without stretching it, sizing a YouTube embed, cropping footage for vertical social platforms, or matching a design mockup to a real screen. Locking the ratio keeps shapes honest: a stretched logo or squashed face is instantly recognisable and instantly amateur.
Frequently asked questions
How is the ratio calculated?
New height = new width × (original height ÷ original width). The ratio between the two original sides is a constant multiplier — the tool applies it in whichever direction you need.
Can I enter a ratio like 2.35:1 directly?
Yes — put 2.35 in the original width box and 1 in the original height box, then enter either new dimension.