Aspect Ratio Calculator
Resize while keeping the ratio.
Runs entirely in your browser — nothing you enter is uploaded, logged, or tracked.
Lock an aspect ratio (16:9, 4:3, 1:1, or your own) and enter either dimension to get the other — no more squished images or letterboxed video.
Frequently asked questions
What does 16:9 mean?
It’s the ratio of width to height: for every 16 units of width there are 9 of height — the standard for modern video and most screens.
Can I use a custom ratio?
Yes — set any width:height ratio, then type a target width or height and the matching dimension is computed instantly.