Image and design
Aspect Ratio Calculator
Calculate one dimension while preserving a ratio
🔒 See this tool’s privacy notes for local processing and external service details. Site analytics are described in our privacy policy.
Quick guide
What can Aspect Ratio Calculator help you do?
Enter a positive width-to-height ratio and exactly one known dimension to calculate the matching width or height.
Best for
Use this when you know a target width-to-height ratio and one dimension and need the other, such as finding a height for 16:9 artwork. It calculates numbers only; it does not inspect, resize, crop, or simplify an existing image's proportions.
How to use it
Enter positive ratio width and height, then fill exactly one known-dimension field and leave the other empty. Defaults are 16:9 with known width 1920. To work from height, clear that default width before entering the known height.
How to read the result
Results are width x height. Calculated height is known width times ratio height divided by ratio width; the reverse calculation finds width. Defaults produce 1920 x 1080. The calculated side is rounded to a whole number, while your supplied side is retained.
Privacy and limits
Multiplication and division run directly in the browser. There is no image upload, remote calculation endpoint, or size-history storage in this code. The answer only appears on the page; the tool does not modify existing images or generate a resized file.
Both known fields filled, or both empty, are invalid; zero and negative dimensions are also unsuitable. Use matching units. Rounding small outputs can alter the exact ratio, and extreme values may overflow. Confirm practical pixel dimensions before creating or exporting an image.
Frequently Asked Questions
Is this tool free?
Yes. It runs in your browser and does not require sign-in.
Is the result exact?
The result is a practical estimate or conversion. For tax, medical, legal, or financial decisions, verify with a qualified source.