Math, Science & Calculators · Free Tool
Aspect Ratio Calculator
Keep an aspect ratio when resizing — enter the original size and one new dimension to get the other, and see the simplified ratio. Runs in your browser.
Original size
New size — fill either box, the other follows the ratio
Aspect ratio
—
Decimal
—
How it works
The original width and height set the ratio. When you type a new width, the new height becomes width × (h₁ ÷ w₁) — and vice-versa — so proportions are preserved exactly. The aspect ratio is the width:height reduced by their greatest common divisor (e.g. 1920×1080 → 16:9). All maths runs locally.