About this aspect ratio calculator
An aspect ratio is the shape of a rectangle expressed as width to height — for example 16:9 (widescreen video and most monitors), 4:3 (older screens) or 1:1 (a square social post). It describes the proportions no matter the actual pixel size. This free calculator does two jobs. The find the ratio section takes any width and height and reduces them to their simplest ratio, plus a decimal version. The resize section helps you scale an image or video without distorting it: give it the ratio and one new dimension, and it works out the other so everything stays in proportion. It is handy for photographers, video editors, designers and anyone fitting content to a screen. All the maths runs in your browser.
Frequently asked questions
- What is an aspect ratio?
- The shape of a rectangle written as width:height, like 16:9 — the proportions, regardless of pixel size.
- How do I resize without stretching?
- Keep the same ratio: enter the ratio and one new dimension, and the tool gives the matching other side.
- What is 16:9?
- The widescreen ratio used by most TVs, monitors and online video — e.g. 1920 × 1080 pixels.