Aspect Ratio Calculator
Turn any width × height into a clean ratio like 16:9, or pick a ratio and complete the missing side — for video, photos and screens alike.
All the maths happens in your browser — the dimensions you type never leave your device.
FAQ
Which aspect ratios are the common ones?
16:9 covers most video, monitors and TVs, and 9:16 is its vertical twin for phone screens and short-form clips. Photos from most cameras come out at 3:2, older screens and iPads use 4:3, 1:1 is the classic square, and ultrawide monitors stretch to 21:9. The presets in the second mode cover all of these.
How does the tool simplify a ratio?
It divides both sides by their greatest common divisor: 1920 × 1080 share a factor of 120, which reduces them to 16:9. When the sides barely share a factor — 1366 × 768 only reduces to 683:384 — the closest-standard row tells you which familiar ratio it almost matches, and by how much it misses.
What if the completed side isn’t a whole number?
Pixels can’t be fractional, so round to the nearest whole pixel — 16:9 at 1000 px wide gives a height of 562.5, which you’d make 562 or 563. The tool shows the exact value, so you can see how far the rounded size drifts from the true ratio.