The Aspect Ratio Calculator reduces an image or video width and height to the simplest whole-number ratio and returns the decimal width-to-height value.
Calculation method
The calculator rounds the entered dimensions to whole numbers, finds their greatest common divisor, and divides both dimensions by that divisor:
Worked example
For a 1920 by 1080 frame, the greatest common divisor is 120. Dividing both values by 120 gives 16:9, and the decimal ratio is 1920 / 1080 = 1.7778.
Frequently Asked Questions
Does the ratio depend on pixels or inches?
No. Aspect ratio is dimensionless, so 1920x1080 and 16x9 describe the same shape.
Why is the result sometimes approximate?
If dimensions do not reduce to a neat whole-number ratio, the simplified result uses rounded inputs and the decimal ratio preserves the measured proportion.
Can I use this for video formats?
Yes. The same width-to-height relationship describes common video frames, image canvases, and responsive containers.
Limitations
The calculator requires positive numeric width and height values. It does not crop, resize, inspect image files, or account for pixel aspect ratio metadata.