Why do my photos get cropped when printed?

Standard print sizes like 6x4 inch (3:2) and 7x5 inch (7:5) have fixed shapes that rarely match every sensor. When the print is a different ratio than your photo, the lab either crops the long edge to fill or adds white borders to fit.

Which print size matches a 3:2 sensor exactly?

6x4 inch, 9x6 inch, 12x8 inch, and 18x12 inch are all exactly 3:2, so a full-frame or APS-C photo fills them edge to edge with no cropping. The classic 7x5 and 10x8 sizes are not 3:2 and will crop.

What about Micro Four Thirds at 4:3?

A 4:3 sensor matches 8x6 inch and many A-series sizes more closely than 3:2 print sizes. The tool ranks every standard size by crop so you can pick the one that loses the least image.

How is the crop percentage calculated?

The tool fills the print with your image and crops the longer dimension to fit. The crop percentage is the fraction of the longer edge that falls outside the print, so 0 percent means a perfect aspect-ratio match.

Does sensor resolution matter for this?

No. Aspect ratio is purely a shape comparison, independent of megapixels. Resolution affects how large you can print sharply, but not whether the shape matches the paper.

Sensor Aspect Ratio to Print Size Matcher

This tool matches your camera’s native aspect ratio against the print sizes a lab actually offers, so you know in advance which ones fill the paper edge to edge and which will crop your image. No more surprise white borders or a head cropped off at the print counter.

How it works

Every image and every print size has an aspect ratio — the long edge divided by the short edge. A 3:2 sensor has a ratio of 1.5; a 6x4 inch print is also 1.5. When the two match, the image fills the paper perfectly.

When they differ, filling the print means cropping the longer dimension of the image. The tool computes the crop like this:

imgRatio   = sensor long / sensor short
printRatio = print long  / print short

It orients the print to best fit the image, then the fraction of the image’s long edge lost is:

crop = 1 - (min(imgRatio, printRatio) / max(imgRatio, printRatio))

A crop of 0 is a perfect match. A 3:2 image on a 7:5 (1.4) print loses about 1 - 1.4/1.5 = 6.7% of its long edge.

Why ratios differ

3:2 — most DSLRs and mirrorless cameras (full-frame and APS-C). Matches 6x4, 9x6, 12x8, 18x12 inch exactly.
4:3 — Micro Four Thirds, many compacts and phones. Matches 8x6 inch and sits close to ISO A-series paper.
16:9 — video frames and some stills modes. Always crops on standard photo paper.
1:1 — square mode. Matches square prints; crops everything else.

Tip

If you know in advance you will print at a non-matching size, compose with head room at the edges so the lab’s crop removes background rather than your subject. Many cameras can overlay print-ratio guides in the viewfinder for exactly this. All comparisons run locally in your browser.