Resize images and video while keeping the aspect ratio, or simplify a pixel resolution to a ratio like 16:9
Enter a ratio, then type a known width or height to compute the other dimension proportionally.
Enter pixel dimensions (e.g. 1920 × 1080) to get the simplified aspect ratio.
To resize while keeping an aspect ratio, enter your ratio like 16:9 and a known width or height, and the calculator fills in the missing dimension. You can also enter a pixel resolution such as 1920x1080 to simplify it to its ratio. It runs in your browser and is free with no signup.
An aspect ratio describes the proportional relationship between the width and height of an image or screen. It is written as two numbers separated by a colon, such as 16:9 or 4:3. The most common widescreen ratio today is 16:9, used by most TVs, monitors, and online video.
This calculator does two jobs. The ratio solver keeps a fixed ratio while you resize: type a new width and the correct height appears automatically (and vice versa), so images never stretch or squash. The resolution simplifier reduces any pixel resolution to its lowest-terms ratio using a greatest common divisor, so 1920 × 1080 becomes 16:9.
Common ratios: 16:9 (HD/4K video), 4:3 (older monitors, tablets), 21:9 (ultrawide/cinema), 3:2 (photography), and 1:1 (square social posts).
