Aspect Ratio Calculator
Two tools in one: paste pixel dimensions (e.g. 1920×1080) to get the simplified ratio (16:9), or enter a ratio and one known dimension to calculate the other. Useful for video, design, and responsive image work. Runs in your browser.
Reduce width and height to a simplified aspect ratio, or use a known ratio and one dimension to calculate the matching width or height. Both modes update in the browser without uploading any data.
How to use the aspect ratio calculator
- Choose Simplify to reduce a width and height to their smallest whole-number ratio.
- Enter both dimensions and copy the resulting ratio if needed.
- Choose Scale when you already know the target ratio.
- Enter the ratio and either a known width or known height to calculate the other dimension.
Simplifying and scaling ratios
Simplify mode uses the greatest common divisor of two positive integer dimensions. For example, 1920 × 1080 reduces to 16:9 because both values can be divided by the same greatest common divisor.
Scale mode preserves the ratio using proportional arithmetic. If you provide a known width, the height is width × ratio height ÷ ratio width. If you provide a known height, the width is calculated in the opposite direction and rounded to at most four decimal places.
Privacy and limitations
All arithmetic runs locally in the browser. Simplify mode expects positive whole-number dimensions, while scale mode accepts positive decimal values. The calculator does not resize image files or inspect media metadata; it only calculates numeric dimensions and ratios.
Frequently asked questions
What does 1920 × 1080 simplify to?
It simplifies to 16:9.
Can I calculate a missing height?
Yes. In Scale mode, enter the ratio and a known width.
Can I calculate a missing width?
Yes. Enter the ratio and a known height.
Can both known width and height be entered at once?
The interface treats them as alternatives and clears the other field when you type one.
Does this tool resize images?
No. It only calculates ratios and dimensions.