Passport photo measurements explained: chin to crown, mm and pixels

Passport photo rules are written in a handful of terms that nobody explains: chin to crown, 35 x 45, 2 x 2, 70 to 80 percent, 3R, 600 px. Each one is a different kind of measurement, and mixing them up is how a correct photo ends up the wrong size. This guide takes them one at a time, with the figures the authorities themselves publish.

Print size: width by height

The print size is the outside of the photo. It is written width first almost everywhere: 35 x 45 mm means 35 mm wide and 45 mm high, and it is by far the most common size among the countries we cover. The United States uses a square of 2 x 2 inches, which photo labs write as 51 x 51 mm because two inches is 50.8 mm. Canada uses 50 x 70 mm, and a Chinese visa photo is 33 x 48 mm.

One trap: Spain writes its size height first. The Ministry of the Interior asks for a photo "tamaño 32 x 26 mm", which is 26 mm wide and 32 mm high, the Spanish carné size. Read as width first it would be a landscape photo, which no authority wants. See the Spanish requirements.

Chin to crown: the head height

Chin to crown is the height of the head inside the photo, from the bottom of the chin to the top of the head. It is the measurement that gets most home photos rejected, because the print can be the right size while the head in it is too small or too large.

The figures differ by country. The U.S. Department of State asks for 1 to 1 3/8 inches, 25 to 35 mm, on the 2 x 2 inch print. The United Kingdom asks for 29 to 34 mm on a 45 mm high photo. Germany gives 32 to 36 mm, Canada 31 to 36 mm on its 70 mm print, and the Chinese embassy in the UK 28 to 33 mm for a visa photo. The same face therefore needs a different crop for each country, which is why the tool measures the head rather than just cutting the frame. See the U.S. rules and the UK rules.

Percentages: "70 to 80 percent" and "80 percent face"

Some authorities give the head as a share of the photo height instead of in millimetres. Germany expresses its 32 to 36 mm as the face filling 70 to 80 percent of the height. That 70 to 80 percent band is also the general portrait rule in ICAO Doc 9303, the international standard for machine-readable passports, which is where the search phrase "80 percent face" comes from. Canada's online renewal image uses a different share, 45 to 50 percent, because the frame is taller.

Where an authority publishes no head height at all, the ICAO band is a sensible target, but it is not that country's own rule. Country pages on this site label it as the general rule when that is all there is.

Pixels and dpi

A printed millimetre has no pixel count until you choose a resolution. The conversion is pixels = millimetres / 25.4 x dpi. At 300 dpi a 35 x 45 mm photo is about 413 x 531 pixels, and a 2 x 2 inch photo is 600 x 600.

For an upload, dpi on its own means nothing; the pixel count is what the portal checks. The UK asks for at least 600 pixels wide, Canada's online renewal at least 1200 pixels wide, and the Chinese visa portal at least 354 pixels wide. The digital sizes guide lists more.

3R, 4 x 6 and other print names

Photo labs name prints by their paper, not by the photo on them. A 3R print is 3.5 x 5 inches, 89 x 127 mm. Bangladesh asks e-passport applicants under six for a 3R print on a grey background; adults are photographed at the office instead. A 4 x 6 inch (10 x 15 cm) print is the standard lab size that several passport photos are laid out on and then cut from, which is what the print sheet from this tool is for. See printing at home or in a shop.