Image aspect ratio calculator
Find the simplified aspect ratio of your images (16:9, 4:3, 3:2...), or calculate the width or height corresponding to a given ratio. Everything is calculated instantly, with no file upload.
Dimensions → simplified ratio
Simplified ratio: 16:9 — i.e. 1.7778:1
Ratio → dimensions
For a width of 1920 px at 16:9, the height must be 1080 px.
For a height of 1080 px at 16:9, the width must be 1920 px.
How it works
The aspect ratio of an image is the relationship between its width and height, simplified to its smallest integer form (for example, 1920×1080 simplifies to 16:9). The first block calculates this simplified ratio using the greatest common divisor of the two dimensions; the second does the reverse, inferring the missing width or height to match a target ratio, useful for resizing an image without distorting it.
Why isn't the simplified ratio always a "round" number?
If the dimensions don't match any standard format (for example, a 1366×768 screenshot), the simplified ratio may consist of large numbers rather than a known format like 16:9. That's normal: the tool then shows the true irreducible fraction, as well as its decimal value for comparison with common formats.
What is the point of calculating a dimension from a ratio?
Very useful before cropping or resizing: by knowing the target ratio (e.g., 16:9 for a video thumbnail) and one fixed dimension (often the width), the tool directly gives the other dimension to use so you don't distort the image or have to guess to the nearest pixel.
100% local calculation: no image is uploaded, everything is calculated instantly in your browser.