Passport Photo Size Guide

A passport photo is defined by two numbers: its physical size in millimetres and its resolution in dots per inch. Get those right and the file is the correct shape and sharp enough to print. Most authorities want 300 DPI, and the sizes range from the US 2-by-2-inch square to the common 35-by-45-millimetre European rectangle.

This guide gives you every common size in both millimetres and pixels, shows the conversion so you can check any size yourself, and is honest about the one thing that matters most: a tool that resizes a photo cannot tell you whether the photo will be accepted. That part is on you, and this guide explains exactly why.

What DPI actually is

DPI stands for dots per inch, and it is the most misunderstood number in image editing. A digital image is just a grid of pixels — say 413 across and 531 down. That grid has no physical size. It is not '35 millimetres wide' until something decides how many of those pixels to pack into each inch of paper. DPI is that decision.

So DPI is really two things bolted together: a pixel count, and a small piece of metadata that says how tightly to print them. At 300 DPI, 300 pixels are printed into every inch. The same 600-pixel-wide image is 2 inches wide at 300 DPI, or 6 inches wide at 100 DPI — same pixels, different printed size, because you told the printer to spread them out.

A digital file has no physical size. DPI is the instruction that gives it one, the moment it is printed.

This is why 'make it 35 by 45 millimetres' is only half an instruction. Millimetres alone do not tell a computer how many pixels to produce. You need the DPI to turn a physical size into a pixel count, and that is exactly what the formula below does.

The one formula you need

There are 25.4 millimetres in an inch. To convert a millimetre measurement into pixels at a given resolution, divide by 25.4 to get inches, then multiply by the DPI:

pixels = mm / 25.4 * DPI

Worked example. A 35-millimetre edge at 300 DPI:

35 / 25.4 = 1.3780 inches
1.3780 * 300 = 413.4 pixels  ->  413 px

That is the whole trick. A 35-millimetre side is 413 pixels at 300 DPI, and a 45-millimetre side is 531 pixels. Every row in the table below is the same sum run twice, once for width and once for height.

Official sizes at 300 DPI

These are the standard photo dimensions for eight of the most-requested countries, converted to pixels at 300 DPI with the formula above. The US size is defined in inches (2 by 2), which is exactly 600 by 600 pixels at 300 DPI; 51 millimetres is the rounded metric equivalent.

The passport photo maker has these sizes built in as presets, so you can crop to the right shape and export at the correct pixel dimensions and 300 DPI without doing the arithmetic yourself.

Getting the crop and pixels right

The dimensions are the part a tool can genuinely help with, so it is worth doing carefully. The order that works best:

1. 1Start with a photo that already has more pixels than your target — enlarging a small image to reach 413 or 600 pixels just invents blur, because the detail was never captured.
2. 2Crop to the correct aspect ratio first (35:45 or 1:1), so the shape is locked before you touch the pixel count.
3. 3Resize the crop to the exact pixel dimensions from the table.
4. 4Export at 300 DPI, and only compress lightly if you need a smaller file for an online form.

For the shape, the image cropper lets you set a fixed ratio and drag a pixel-precise selection; for the final pixel size, the image resizer hits an exact width and height. If an online application caps the upload size, the image compressor can bring the file under the limit — but compress gently, because heavy compression on a face is exactly the kind of degradation a reviewer notices.

All of this runs in your browser. Your photo — which is, after all, a government-facing picture of your face — is never uploaded to Pixora. The crop, the resize and the compression happen entirely on your own device.

What a tool cannot do for you

This is the part worth repeating, because it is where people get burned. Every requirement below is a rule a human reviewer applies, and none of them are things a resizing tool can measure or fix:

• Head-height ratio — how much of the frame your head fills, measured chin to crown, with tight tolerances that vary by country.
• Background — usually a plain white or light grey with no shadows, texture or objects behind you.
• Expression and eyes — neutral face, mouth closed, eyes open and clearly visible, looking straight at the camera.
• Glasses — many countries now ban them outright to avoid glare and frame obstruction.
• Head coverings — permitted only for religious or medical reasons, and even then the full face must be visible.
• Lighting and shadows — even illumination, no red-eye, no shadows on the face or behind the head.

Quick answers

How do I convert 35 mm to pixels?

Divide by 25.4 to get inches, then multiply by the DPI. At 300 DPI, 35 divided by 25.4 is 1.378 inches, times 300 is 413 pixels.

Is a US passport photo 600 by 600 pixels?

Yes, at 300 DPI. The US size is 2 by 2 inches, and 2 inches times 300 dots per inch is exactly 600 pixels on each side.

Will a correctly-sized photo be accepted?

Not automatically. Correct dimensions are necessary but not sufficient — background, head size, expression and lighting all have to pass too. Always check the official rules for your country and document.