35x45mm, and a head window tighter than you'd think
A UK passport photo is 35mm wide by 45mm tall. Inside that small frame, HM Passport Office requires the head - chin to crown - to measure between 29mm and 34mm, a narrower window than several other countries use even at the same canvas size. A photo that's exactly 35x45mm with a head outside that 5mm range is rejected just as often as a photo cropped to the wrong size, which is why the guide lines here are the part that matters - the crop is just what happens once your head sits between them.
Where UK rules differ from what you might expect
- Background: plain, light-coloured - cream or light grey recommended, not pure white. That's the US standard, not the UK one, and it's a common mix-up.
- Glasses: allowed if you normally wear them, provided there's no glare on the lenses and your eyes are clearly visible through them.
- Expression: neutral is standard; a slight, closed-mouth smile is generally tolerated, unlike some countries' stricter neutral-only rule.
- Cropping from a larger photo: not accepted - the photo must be taken specifically for this purpose, not cropped out of a holiday snap or group photo.
- Recency: a genuinely current photo, not a favourite from a few years back - check the exact window on the application itself, as services vary.
This tool gets the size and head placement right, which is the most common technical reason UK passport photos are rejected. It can't judge your lighting, background colour or expression - that part is on the photo itself.
Taking the photo yourself
A phone camera works fine if the technique is right. Avoid a selfie at arm's length - the short distance distorts your nose and compresses your facial proportions in a way that can look subtly wrong and occasionally fails automated checks. Have someone else take the photo from about two metres away with a standard lens, not an ultra-wide one.
Stand a little forward of your background so you don't cast a shadow on it, and use soft, even light - daylight from a window, or two lights angled from either side. Direct flash straight at the face tends to blow out detail and create harsh shadows under the chin, which is a common reason for a retake.
Digital upload vs. a printed photo
UK online passport applications accept a digital upload directly - this tool's 300 DPI setting produces roughly 413×531 pixels for a 35x45mm photo, comfortably above what the online system expects. If you're applying on paper or need a physical copy for another reason, use the print sheet option to lay several copies out on a 4×6 inch sheet with cut lines, ready for a standard photo print at a pharmacy or supermarket kiosk.
Resolution
300 DPI is the default and the sensible choice for most people, giving a sharp result for both the digital upload and a physical print. Use 600 DPI only if you specifically need extra detail for an enlarged print; going lower risks a soft result that an upload checker may reject before a human even looks at it.
Everything runs in your browser using the canvas API - the photo is never sent to a server. There's no account, no sign-up, and no file size limit beyond what your device can handle.