How to use this calculator
Enter the source pixel dimensions and the two parts of the target aspect ratio. Use 1 and 1 for a square, or 16 and 9 for a landscape frame. This reports crop geometry; it does not upload or edit your photo.
The formula
A worked example
A 6,000 × 4,000 image cropped to 16:9 becomes 6,000 × 3,375, retaining 84.375% of its pixels. A centered crop removes 312 pixels from the top and 313 from the bottom. A square crop is 4,000 × 4,000.
Assumptions & limitations
Uses the largest exact-ratio rectangle with whole-pixel dimensions, without rotation, resizing, or subject-aware positioning. Odd leftover pixels are split with the extra pixel on the right or bottom. Small source images may not fit one exact ratio block.
Common questions
Why are the top and bottom margins sometimes different?
An odd number of discarded pixels cannot be split equally into integer margins. One side receives the extra pixel.
Does cropping change print resolution?
Cropping removes pixels. Use the remaining dimensions in the photo print-size calculator to choose a physical size at your desired PPI.
Supporting reference
The method above states this calculator’s assumptions. This reference provides related definitions and technical context.
Adobe Photoshop: crop tool options ↗Formula and worked example checked against automated test cases. About our methodology.