Why 5×7 and 11×14 Always Need a Crop
Every camera on the market shoots a rectangle in a fixed proportion. Most interchangeable-lens cameras shoot 3:2. Most phones shoot 4:3. Print sizes, meanwhile, evolved separately, and a surprising number of the standard ones match neither.
Run the common frame sizes through the aspect ratio calculator and the pattern is immediate:
- 4×6 → 2:3
- 5×7 → 5:7
- 8×10 → 4:5
- 11×14 → 11:14
- 12×16 → 3:4
- 16×20 → 4:5
- 18×24 → 3:4
- 24×36 → 2:3
Two sizes reduce to themselves
Look at 5×7 and 11×14. They do not simplify. 5 and 7 share no common factor, and neither do 11 and 14 — the calculator returns 5:7 and 11:14 unchanged, because those fractions are already in lowest terms.
That is not a quirk of arithmetic; it is the practical fact that no camera shoots 5:7 or 11:14. A 4×6 print takes a 3:2 file with no crop at all. A 12×16 or 18×24 takes a 4:3 phone photo untouched. But a 5×7 and an 11×14 will always require you to throw something away, whatever you shot it on.
Which sizes are actually free
Working from the two dominant camera ratios, the pairings are straightforward. If you shoot 3:2, the sizes that need no crop are 4×6, 24×36 and 20×30. If you shoot 4:3 on a phone, they are 12×16 and 18×24. Everything else on the list costs you image area.
This is worth knowing before you shoot, not after. Composing with a little air around the subject — knowing you will crop to 4:5 for an 8×10 — is free at the time and impossible afterwards.
The most common surprise: 8×10
8×10 is the size people default to, and it is 4:5 — narrower than both 3:2 and 4:3. It is the single most common source of "the printer cut off my subject's head", because the ratio mismatch is large and it always trims the long dimension.
The fix is not to avoid 8×10; it is to decide the crop yourself rather than letting a print service decide it. Every service applies some default, and the default is a centred crop, which is right for a centred composition and wrong for almost everything else.
Ratios do not care about size
One useful consequence of reducing to lowest terms: 8×10 and 16×20 are the same shape. So are 4×6, 20×30 and 24×36. A crop prepared for one works for the other without redoing anything, which means a single 4:5 export covers both an 8×10 desk frame and a 16×20 on the wall.
This is also why "8×10" and "16×20" mats are interchangeable in proportion even though nothing else about them is. If you are ordering several sizes of the same image, group them by reduced ratio first and you will find you need far fewer crops than prints.
Non-integer sizes reduce too
The calculator rounds fractional dimensions to a fine grid before reducing, so a print measured at 8.5×11 — standard letter paper — is handled as readily as a whole-inch size. It reduces to 17:22, another pair that shares no factors, which explains why letter-size art is awkward to fit into any standard photo frame.
If you are working with an unusual size, the reduced ratio is the number to write on the mat order, not the dimensions. Two framers given "17:22" will produce the same shape; two framers given "roughly A4-ish" will not.