Documents
Your document has its own rules. Pick yours.
Each page lists the exact size, head height, background and file limits from the issuing authority — the same numbers the free check applies.
Converting millimetres to pixels? The photo size calculator does the mm-to-px conversion at any DPI and lists every document's published size.
The Passport Photo Maker is an independent service and is not affiliated with any government. Specs come from the issuing authorities' published guidance; only the authority handling your application can approve a photo.