Aspect Ratio Calculator
Reduce width and height to an aspect ratio and calculate proportional dimensions. Free, with no signup or usage-count limits.
Free · No signup · No watermark · On-device processing
Use the tool
How to use Aspect Ratio Calculator
- Enter the original whole-pixel width and height.
- Choose a target width or target height and enter its size.
- Calculate the reduced ratio and the matching target dimensions.
How the result is calculated
Positive whole-number source dimensions are reduced by their greatest common divisor. Enter a target width or height to calculate its proportional counterpart, rounded to the nearest whole pixel.
Rounded pixel dimensions can only approximate some ratios. This calculator does not resize an image itself; use Resize Image to create the actual file.
Privacy and browser support
Your input is handled in this browser tab. Selected files and entered text are not sent to Varento Tools by this tool. Some specialized libraries load only when needed. A browser with JavaScript and sufficient device memory is required. Read our local-processing explanation.
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Frequently asked questions
Is this tool free without daily usage limits?
Yes. Varento Tools has no signup, accounts, usage-count caps, paywalls or watermarks. Device memory, format support and browser restrictions can still limit technically demanding files.
Why can a rounded result differ slightly from the original ratio?
Images use whole pixels. Some proportional dimensions are fractional, so the calculated side is rounded to its nearest pixel. Use a larger target when that rounding matters.
Is my input uploaded?
No. This tool processes your input in the current browser tab and does not send it to a processing server.
What are the practical limits?
Rounded pixel dimensions can only approximate some ratios. This calculator does not resize an image itself; use Resize Image to create the actual file.