Aspect Ratio Calculator
Calculate a missing dimension from a known aspect ratio (16:9, 4:3, 1:1...), or find the simplified ratio of any two dimensions. Useful for video editing, layout, or web design—with no data sent to a server.
How it works
An aspect ratio (for example 16:9) expresses a proportion between width and height: this tool uses a simple rule of three to find the missing dimension from the other one, or calculates the greatest common divisor of two dimensions to reduce a ratio to its simplest form (for example 1920×1080 becomes 16:9).
When should I use "calculate a dimension" instead of "find the ratio"?
Use the first mode when you know the target format (a 16:9 video, a 3:2 photo) and only one dimension, to find the other without distorting the image or layout. Use the second mode when you already have two precise dimensions and want to know which "standard" ratio they match, or simply reduce them to their smallest equivalent form.
Can the result contain decimal places?
Yes, if the calculated dimension is not a whole number of pixels, the result is rounded to two decimal places: in that case, round it to the nearest whole number according to your use context (a pixel count must remain an integer for on-screen use).
The calculation is performed entirely in your browser, with no data transmitted to a server.