Crop to Aspect Ratio Calculator
Find the largest crop that fits a target aspect ratio inside an image.
What this tool calculates
Find the largest crop that fits a target aspect ratio inside an image. The main inputs on this page are Image width (px), Image height (px), Target ratio width, Target ratio height. The result is intended to be readable immediately, with the explanation below available when you need to verify the method.
Method and calculation basis
Aspect ratio is width:height reduced by their greatest common divisor. A missing dimension is found by preserving width ÷ height.
Worked examples
1920 × 1080
Both dimensions divide by 120, giving 16:9.
16:9 at 1920 px wide
Height = 1920 × 9 ÷ 16 = 1080 px.
Understanding the result
The output should be read in the units shown beside the result. If you are comparing alternatives, keep all unchanged assumptions identical and alter one input at a time. That makes it easier to see which value is responsible for the difference.
Assumptions, edge cases and accuracy
Dimensions and PPI are mathematical properties; they do not guarantee visual quality. Compression, resampling, focus and source quality still matter.
Sources and methodology
- W3C — Web image and browser standards where applicable
- Printer/image workflow documentation — PPI, dimensions and output-device requirements
Method reviewed for Instant Solvers V10.0 · October 2026. If you find a calculation or explanation that needs correcting, use the site Contact page and include the tool URL and the values you entered.