UK Passport Photo Size: 35 x 45mm, and the rules that go with it

Thirty-five millimetres wide by forty-five millimetres high is the number almost everyone arrives looking for, and it is the easy half of the specification. It matches what UK photo booths have produced for decades, which is why a booth strip drops straight into an application without anyone having to think about it.

The harder half is the head measurement. From the crown of your head to the bottom of your chin the image must fall between 29mm and 34mm. That is a five-millimetre window inside a forty-five-millimetre frame, so roughly two-thirds to three-quarters of the height is face. Get the outer rectangle exactly right and the head wrong and the application still fails, which is the single most common way a home-cropped photo comes back.

Working backwards is easier than guessing. Decide where the chin sits, decide where the crown sits, and let the frame follow from those two points rather than cropping a pleasing rectangle and hoping the face lands correctly inside it.

Applying online replaces millimetres with pixels. The photo must be at least 600 pixels across and 750 tall, and the file must weigh between 50KB and 10MB. The proportions are the same 35:45 relationship expressed at a different scale, so a correctly composed print and a correctly composed upload are the same photograph.

The lower file-size bound catches people out more than the upper one. Phone gallery apps and messaging apps compress aggressively on share, and a photo that arrives at 40KB is refused for quality even though it looks perfectly sharp on the screen you are looking at. Send yourself the original file rather than a shared copy.

A booth that offers a digital code is doing this step for you. If you are cropping your own, hit the pixel floor with room to spare — 900 x 1125 or larger costs nothing and survives whatever re-encoding happens along the way.

Most countries allow six months. The UK asks for one. In practice nobody measures the age of a photograph forensically, but the rule exists because the passport is supposed to show how you look now, and an examiner comparing your photo to the person at the desk is the check that actually bites.

The practical reading is that a photo from a holiday last year is not usable even if it happens to have a plain wall behind it. If your appearance has changed noticeably — a beard shaved, hair cut short, glasses gone — take a new one regardless of what the date stamp says.

Do not wear glasses unless you have to. If you must, they cannot be sunglasses or tinted, and your eyes cannot be covered by the frames or by any glare, reflection or shadow. The failure mode is almost always reflection rather than the frames themselves, and it comes from a light source directly in front of you.

Head coverings are not permitted unless they are worn for religious or medical reasons, and where they are worn the face must remain visible from the bottom of the chin to the top of the forehead.

Expression is plain and the mouth is closed. Eyes open, visible, and no hair falling across them. This is where a photograph taken casually fails most often — a natural photograph of a person almost always has some expression in it, and the specification is asking for the absence of one.

It does not generate one. A passport photograph has to be a photograph of you, taken recently, and a face produced by an image model is not that regardless of how convincing it looks. Submitting one is document fraud, and no amount of search traffic makes that a service worth offering.

What genuinely helps is the boring part: the free image cropper takes a photograph you already have to the 35:45 proportion with the head where it needs to be, the image resizer hits the 600 x 750 pixel floor exactly, and the image compressor moves a file into the 50KB–10MB band without visible loss. All three run in the browser, so a photograph of your face is never uploaded anywhere.

If the background behind you is cluttered rather than plain, that is a reshoot rather than an edit. Stand roughly a metre in front of a plain light wall, face a window, and have someone photograph you from about a metre and a half away at eye level — distance from the wall removes your shadow, distance from the lens removes the facial distortion that an arm's-length phone photo always adds.