Aspect Ratio Crop Calculator
The largest centred crop matching a target aspect ratio.
Results
- Cropped dimensions
- 4,000 × 4,000 px
The largest crop matching your target ratio that fits within the original image, centered.
How it works
Every output has its own shape. Cameras shoot 3:2 or 4:3, Instagram wants 1:1 or 4:5, video wants 16:9, and print frames come in their own set of sizes that match none of them. Cropping between them always costs pixels.
This gives you the largest rectangle of your target ratio that fits inside the original, which tells you exactly what resolution survives. If the target is wider than the original you lose height; if narrower, you lose width.
It is worth checking before a shoot rather than after. If you know a frame is destined for a 16:9 crop, composing with that in mind, leaving room top and bottom, is far easier than discovering afterwards that the crop cuts through someone's head.
The formula
if target ratio > original: width stays, height = width / target; otherwise height stays, width = height × target
The crop is centred and always the largest one of that ratio that fits inside the original pixel dimensions.
Frequently asked questions
- How many megapixels do I lose?
- Multiply the resulting width and height and compare with the original. Going from 3:2 to 1:1 keeps only about two-thirds of the pixels, since the entire crop is limited by the shorter edge.
- Which ratio should I shoot for social media?
- 4:5 portrait occupies the most screen space in a vertical feed without being cropped, which is why it consistently outperforms square. 1:1 remains the safe choice when an image will appear in mixed grid layouts.
- Does cropping reduce image quality?
- It removes pixels but does not degrade the ones that remain. Quality only becomes an issue if the crop leaves too few pixels for your intended output size, which the print size calculator will tell you.