If you've ever looked at the bottom of your passport and wondered about the strings of capital letters, digits and < symbols, that's the MRZ. It repeats key facts from the page above (name, passport number, nationality, birth date, expiry date) in a fixed format, so a scanner can read them without anyone typing.
The format comes from ICAO Doc 9303, the international standard for travel documents, which refers to the ISO/IEC 7501 multipart standard for machine readable travel documents. Because countries follow it, an MRZ is laid out the same way on passports from different countries.
What a machine-readable zone is
The MRZ is Zone VII on a passport's data page. The rest of the page, which people read directly, is the Visual Inspection Zone. The MRZ adds characters that are easy for a reader to recognize, limited to capital letters, digits and the filler symbol <.
The number of lines depends on the document size:
- TD3, the passport book and similar documents: two lines, 44 character positions each.
- TD1, card-sized documents: three lines of 30 characters each.
ICAO also defines a mid-size, TD2. This page covers the two you're most likely to meet.
The MRZ is not the chip. A biometric passport has both: the printed zone read optically, and a contactless chip read electronically.
What's on it
Here is the layout of a TD3 passport, from ICAO Doc 9303 Part 4. Character positions are counted from the left of each line.
| Line and positions | Field | What to check |
|---|---|---|
| Line 1, 1 to 2 | Document code | Starts with P for a passport |
| Line 1, 3 to 5 | Issuing State or organization | Three-letter code |
| Line 1, 6 to 44 | Name | Surname, then given names, separated by <<; extra positions filled with < |
| Line 2, 1 to 9 | Passport number | Special characters and spaces become < |
| Line 2, 10 | Check digit | For the passport number |
| Line 2, 11 to 13 | Nationality | Three-letter code |
| Line 2, 14 to 19 | Date of birth | Six digits, followed by its own check digit at 20 |
| Line 2, 22 to 27 | Date of expiry | Six digits, followed by its own check digit at 28 |
| Line 2, 29 to 44 | Personal number, then check digits | Check digit at 43, and a composite check digit at 44 |
How check digits work. A check digit is a single digit computed from other digits, so a reader can verify the data was interpreted correctly. The method:
- Going left to right, multiply each digit by a repeating weight of 7, 3, 1, 7, 3, 1...
- Add the products.
- Divide the sum by 10. The remainder is the check digit.
Letters A to Z count as 10 to 35, and < counts as zero. ICAO's own example uses the date 520727: the products are 35, 6, 0, 49, 6 and 7, the sum is 103, and the remainder is 3, so it's written 5207273.
A passing check digit means the characters are consistent with each other. It doesn't prove the document is genuine. To try this on your own MRZ, use the MRZ checker; it's the quickest way to catch a typo in a form that asks you to copy those lines. To find out whether the expiry in the MRZ leaves enough time for a trip, use the passport validity calculator.
What to keep and for how long
The MRZ is part of the document, not a separate record, so what you keep is the passport or card itself, and a copy of its photo page for your own records. A clear, straight-on scan of the data page keeps the MRZ legible, which matters when you have to type it into a visa or airline form.
Keep that copy as long as the document is valid, and see how long a passport is valid and how to check your passport expiration date for the dates. Because it holds a lot of personal data in one place, store the copy somewhere protected, not in a shared photo stream.