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MRZ Parsing

Definition

MRZ (Machine Readable Zone) is a standardized text block on passports, visas, and some national IDs — printed in OCR-B font following ICAO 9303 specifications. MRZ provides machine-readable identity data with built-in error detection through check digits.

MRZ Formats

Type Lines Characters/Line Used On
TD1 3 lines 30 characters each ID cards (CR80 format)
TD2 2 lines 36 characters each Some ID cards, older passports
TD3 2 lines 44 characters each Passports, travel documents
MRVA 2 lines 44 characters each Visa Type A
MRVB 2 lines 36 characters each Visa Type B

MRZ TD3 Structure (Passport)

Line 1: P<UTOERIKSSON<<ANNA<MARIA<<<<<<<<<<<<<<<<<<<
Line 2: L898902C36UTO7408122F1204159ZE184226B<<<<<10
Field Position (Line 2) Example Check Digit
Document number 1-9 L898902C3 Position 10
Nationality — (Line 1) UTO —
Date of birth 14-19 740812 (YYMMDD) Position 20
Sex 21 F —
Expiry date 22-27 120415 (YYMMDD) Position 28
Personal number 29-42 ZE184226B Position 43
Composite check 44 0 Over doc# + DOB + expiry + personal#

Check Digit Calculation

MRZ uses a weighted checksum: weights cycle through 7, 3, 1 for each character position.

def mrz_check_digit(data):
    weights = [7, 3, 1]
    values = []
    for char in data:
        if char == '<':
            values.append(0)
        elif char.isdigit():
            values.append(int(char))
        elif char.isalpha():
            values.append(ord(char) - ord('A') + 10)
    total = sum(v * weights[i % 3] for i, v in enumerate(values))
    return str(total % 10)

Key Takeaways

Summary

  • MRZ provides standardized, machine-readable identity data on travel documents
  • Check digits enable mathematical verification of extracted data — catch OCR errors
  • 99.5%+ accuracy achievable with OCR-B optimized recognition
  • MRZ data can be cross-validated with visually extracted (VIZ) data for additional confidence
  • Essential for passport verification in eKYC