The photo is a biometric template, not a portrait
Almost every country's passport photo requirements derive from ICAO Document 9303, the international standard for machine-readable travel documents. The photo on the page and in the chip is intended to work with automated face recognition at borders, which is why the rules are shaped the way they are.
Face recognition works by locating landmarks — the pupils, the nose, the corners of the mouth and jaw — and measuring the distances between them. Anything that obscures a landmark or distorts a distance breaks the template. A neutral expression is required because smiling moves the mouth corners and changes the jawline. Glasses are restricted because reflections hide the pupils. Head tilt matters because it changes the apparent distance between features.
Understanding this reframes the whole exercise. You are not trying to look good; you are trying to present a clean, undistorted, well-lit set of facial landmarks. Some of the rules that seem arbitrary — no smiling, hair off the face, both ears visible where possible — all follow from that one purpose.
Head size: the most common failure
More photos are rejected for head size than anything else, and it is the hardest requirement to judge by eye.
The measurement is from the bottom of the chin to the top of the head — the crown, including hair volume, not the top of the forehead. Most countries following the international standard want that distance to be 32–36 mm within a 35 × 45 mm frame, which is about 70–80% of the frame height. The UK is tighter at 29–34 mm. Canada wants 31–36 mm within its larger 50 × 70 mm frame. The United States measures differently again, wanting 25–35 mm within a 51 × 51 mm square, which leaves visibly more space around the head than the European convention.
The practical consequence is that photos cannot be moved between countries. A compliant UK photo cropped down to US dimensions has a head that is too large, and a US photo enlarged to European dimensions has one that is too small. If you are applying to two countries, frame each one separately.
The second consequence is that self-taken photos usually fail high rather than low: people fill the frame with their face the way they would for a profile picture, and end up 10 mm over. Shoot wider than feels right and crop precisely afterwards.
Shadows, and why the wall matters
The second most common failure is a shadow — either on the face, or cast onto the background behind the head. Both come from the same cause: standing too close to the wall with light coming from in front of you.
The fix is distance. Stand at least a metre away from the background, ideally more. Your shadow then falls on the floor behind you rather than onto the wall in the frame. This single change eliminates most background shadow problems.
For light on the face, the enemy is a single hard source, especially overhead. Ceiling lights produce dark eye sockets and a shadow under the nose and chin. The best free light source is an overcast day through a large window, with the subject facing the window. Overcast sky is an enormous, even, soft source and is very hard to beat. Direct sunlight is the opposite — small, hard and contrasty — and causes squinting.
Glasses, expression and headwear
The rules here vary more by country than any other category, and assuming your country follows the one you read about is a good way to be rejected.
The United States has banned glasses in passport photos since November 2016, with an exception only for documented medical reasons. China bans them for visa photos with no exception. Australia asks you to remove them. Canada, by contrast, permits them as long as the eyes are clearly visible with no glare and no tint. The UK discourages them but does not forbid them.
Given that spread, the safe move is simply to take them off, unless you are in one of the countries that allows them and you have a reason to keep them on.
Expression rules are more consistent: neutral, mouth closed, both eyes open, looking straight at the camera. The US is the notable outlier in explicitly allowing a natural, unforced smile. The UK is explicit that you must not smile at all. When in doubt, neutral is accepted everywhere.
Headwear is permitted essentially everywhere for religious or medical reasons, and essentially nowhere otherwise. Where it is worn, the full face from the bottom of the chin to the top of the forehead must be visible, and the covering must not cast a shadow across the face.
The rules for babies that surprise people
Infants get latitude on expression and gaze — most countries accept closed eyes for newborns and do not require a neutral expression from under-ones — but they get no latitude at all on one rule: nobody else may appear in the photograph.
That includes a hand supporting the head, an arm at the edge of the frame, the back of a car seat, or a patterned blanket. This is the single most common reason an infant photo is returned, and it catches almost everyone the first time.
The reliable technique is to lay the baby on their back on a plain white or light grey sheet and photograph from directly above, with the camera parallel to the sheet. Natural light from a window, no flash. Take many frames — you are waiting for one where the eyes are open and the head is straight, and that frame is a matter of luck rather than skill.
China is the notable exception to infant leniency: it applies essentially the same head-size specification to babies as to adults, which makes a compliant Chinese visa photo of a newborn genuinely difficult.
Countries where you do not supply a photo at all
Before you spend an afternoon on this, check whether your application even uses a supplied photo. Several countries capture it at the counter.
India's Passport Seva process photographs applicants at the Passport Seva Kendra during the appointment. Portugal captures the photo at the Loja do Cidadão or Conservatória for both the Cartão de Cidadão and the passport. Brazil's Polícia Federal takes the photo at the passport appointment. In all three, turning up with prints is a wasted trip.
Canada sits at the opposite extreme: not only must you supply photos, they must be taken by a commercial photographer, and the back of one print must carry the studio's name, address and the date. A photo produced entirely at home does not satisfy that rule no matter how compliant it is technically.
A workable home procedure
Putting it together, in order:
- Find a plain, light, untextured wall and stand at least a metre in front of it.
- Face a large window on an overcast day. Turn off all indoor lights.
- Have someone else shoot from about two metres away at eye level, zoomed in slightly. Do not use a selfie at arm's length — it distorts the nose and cheeks.
- Remove glasses. Neutral expression, mouth closed, head straight, hair off the face and eyebrows.
- Shoot wider than you think you need, so you have room to crop to the exact head-height requirement.
- Take thirty frames. Blinks and micro-expressions ruin more shots than you would expect.
- Crop to your country's exact dimensions and check the chin-to-crown measurement against its specific window rather than assuming 32–36 mm.