Passport photo size, every country compared

Almost every authority publishes its photo requirements in millimetres, even for digital submissions where the file has no physical size. IRCC, for example, states that the face must measure 31 to 36 mm from chin to crown while also asking for a minimum of 420 by 540 pixels. The millimetre figure is the rule; the pixel figure is a delivery constraint.

This is why converting a specification into pixels requires you to fix a DPI first. At 300 DPI a 35 mm width is 413 pixels; at 600 DPI it is 827. Both are the same physical photo. Any tool that presents pixels without stating a DPI is hiding a decision from you.

Most formats fall into one of four groups. The 35x45 mm ICAO family is by far the largest, covering the UK, Ireland, Germany, France, Australia, New Zealand, Japan, India, Singapore and dozens more. The 2 inch square family covers the United States and Indian visas. The 50x70 mm family covers Canada and Brazil. Everything else is a one-off: China 33x48, Malaysia 35x50, Bangladesh 45x55, Finland 36x47, Spain 26x32, Greece 40x60.

The trap inside the 35x45 group is that the outer dimensions match while the head height rules do not. The UK requires 29 to 34 mm, Ireland 31.5 to 36 mm, Germany 32 to 36 mm, Japan 34 mm plus or minus 2 mm, and Singapore an unusually wide 25 to 35 mm. A photo scaled correctly for one can be out of range for another with no visible difference in the file.

Where a specification is written in inches, the millimetre value here is the exact conversion rather than a rounded one. A 2 inch photo is 50.8 mm, not 51 mm, and a 1 3/8 inch head is 34.9 mm. Authorities do allow small tolerances, but there is no reason to spend your margin on a rounding error before the photo is even taken.