Aspect Ratio Calculator & CSS Preview
Scale dimensions with exact fractions, copy CSS aspect-ratio and compare automatic and fixed heights.
Enabling local controls…
1. Input and options
Runs in page memory, without uploading or saving input. Text input and generated output: 1 MiB UTF-8 each. Copy is explicit; results clear whenever inputs change.
Positive integer inputs up to 1,000,000,000. Fractional output does not imply a valid whole-pixel image size.
2. Result
Enter input or load a sample, then run.
If clipboard access is denied, select the output and copy manually.
CSS aspect ratio
How to use this tool
Enter width and height or choose a preset. Optionally set a new dimension. Calculate, review the exact fraction, and copy the CSS for an automatically sized box.
When not to use it
Positive integer inputs up to 1,000,000,000. Fractional output does not imply a valid whole-pixel image size.
Read the guide →