Passport photo aspect ratios

The aspect ratio answers one question: can this crop be reused without distorting the image? If two formats share a ratio, the same framing works for both and only the export resolution changes. If they do not, reusing the crop means either stretching the photo, which is never acceptable, or cutting into it further.

What the ratio cannot tell you is whether the head will be the right size. That is set by the chin-to-crown rule, which varies independently. Two 7:9 formats can demand head heights 3 mm apart, and 3 mm inside a 45 mm frame is a meaningful difference.

7:9 covers the 35x45 mm international standard and therefore most of the world. 1:1 is the US 2 inch square, also used by Indian visas and OCI cards. 5:7 is Canada's 50x70 mm and Brazil's. 11:16 is China's 33x48 mm, noticeably narrower than everything else. 7:10 is Malaysia's 35x50 mm.

Once you know the ratio, official pixel minimums stop looking arbitrary. IRCC's 420 by 540 is 7:9. Singapore's 400 by 514 is very nearly 7:9. Chinese visa uploads at 354 by 472 and 420 by 560 are both 3:4, which is close to but not exactly the 11:16 print ratio, reflecting the fact that the digital rule was written separately.

Consumer cropping tools let you lock an aspect ratio and drag a box. That guarantees the shape and nothing else. The specification is a measurement of your head inside that shape, and no cropping app measures your chin and crown. This is the gap the editor on this site closes: it calculates the crop from your actual facial geometry and reports the head height in millimetres so you can verify it.