What is the MRZ? Your passport’s machine-readable zone, decoded

At the bottom of every passport's data page sit two 44-character lines of capitals, digits and chevrons — the machine-readable zone. Airlines, border gates and scanners read those lines, not the pretty printed text above.

What’s encoded

Line 1: document type, issuing country, and your name — surname, then <<, then given names, with < as both space and padding (DOE<<JANE<MARIE<<<…). Line 2: passport number, nationality, date of birth, sex, expiry date — each followed by a check digit. The format (ICAO 9303) is identical worldwide, which is why one reader design works at every border on earth.

Check digits: math against misreads

Each numeric field's digits are weighted (7,3,1 repeating), summed, and the remainder mod 10 is printed as the check digit. A scanner re-computes it: mismatch = misread = try again. It's why MRZ reading achieves near-perfect accuracy from cheap cameras — the zone proves it was read correctly. ToPDF uses exactly this: check-digit validation tells it a real MRZ (and thus the data page) is present, powering both accurate name suggestions and the automatic keep-the-data-page crop for photographed passport books.

Practical consequences for your scans

• The MRZ is the part machines need: keep both lines complete and sharp in any passport copy. (Scanning guide.)
• It's as sensitive as it is useful: those lines are your identity in machine form — treat any image containing them like the passport itself.
• OCR-B, the font, was designed in the 1960s for machine legibility; its distinct glyphs are why even partial glare often still validates.

Frequently asked questions

Why chevrons (<) instead of spaces?

Fixed-width fields need an unambiguous filler that no name contains and every reader recognises — the chevron is visually and mechanically unmistakable.

Do ID cards have MRZs too?

Many do — typically three shorter lines (TD1 format) on the back. The same check-digit logic applies, and ToPDF reads those as well when present.