PassportPhotoGuide is a reference site for one narrow, badly explained problem: the size and composition rules that passport and visa photos have to satisfy. It is run by a small independent team that has spent more time than is reasonable comparing the photo pages of passport agencies, visa centres and immigration services, and translating them into numbers a person can check at home.
The site exists because the information is technically public but practically scattered. A US passport photo is 2 × 2 inches with a head between 25 mm and 35 mm; a UK digital photo must be at least 600 × 750 pixels and taken within the last month; a Chinese visa photo is a narrow 33 × 48 mm block; a Canadian photo is 50 × 70 mm with a 31–36 mm face. Each of those facts lives in a different government page, in different units, surrounded by paragraphs about other things. A person applying for one document does not need the other seven — until they do, which is usually the day before an appointment.
Three commitments shape the site. First, every specification is tied to the official page it came from and the date it was last checked; the methodology page describes that process, including what happens when an official page cannot be reached. Second, the checker runs entirely in the visitor's browser — the photo is read into a canvas element and measured there, no file is transmitted, and there is no server-side copy to lose. Third, the site tells you what it cannot do: a browser measurement is a fast first pass, not an official decision, and no page here replaces the checklist that comes with your application.
Corrections are genuinely welcome. Photo rules change quietly and a wrong number on this site is worse than no number at all, so reports that point at an official page contradicting something here get fixed first. Write to hello@passportphoto.buyerguidehq.com.