Check machine-readable passport fields.
Initialising algorithm engine for Passport MRZ Check Digit Calculator...
How Passport MRZ Check Digit Calculator Works?
The Passport MRZ Check Digit Calculator works by converting each field character to a value (digits as is, A = 10 … Z = 35, filler < = 0), multiplying by the repeating weights 7, 3, 1, and taking the sum modulo 10. ICAO Doc 9303 defines 5 check digits on the 2nd line of a passport machine-readable zone (MRZ).
- 1Read the field from the 2nd MRZ line: document number, birth date, expiry date, or optional data.
- 2Convert digits to 0–9, letters to 10–35, and the filler < to 0.
- 3Multiply the values by 7, 3, 1, 7, 3, 1… from the left.
- 4Add the products and take the remainder modulo 10.
- 5Compute the composite check digit over positions 1–10, 14–20, and 22–43 of line 2.
Passport MRZ Check Digit Calculator Formula
The MRZ formula is Check = (Σ v(cᵢ) × w₍ᵢ mod 3₎) mod 10, with weights 7, 3, 1.
S = Σ v(cᵢ) × wᵢ, w = 7,3,1,7,3,1… Check = S mod 10 v: 0–9 → 0–9, A–Z → 10–35, '<' → 0
v(c)is the character value.
Document number: L898902C3 → 316 mod 10 = 6 Date of birth: 740812 → 122 mod 10 = 2 Date of expiry: 120415 → 49 mod 10 = 9 Optional data: ZE184226B<<<<< → 401 mod 10 = 1 Composite → 880 mod 10 = 0 Line 2: L898902C36UTO7408122F1204159ZE184226B<<<<<10
Passport MRZ Check Digit Calculator Conversion Table
The MRZ conversion table lists the 5 check digits on line 2 of the ICAO specimen passport.
| Field | Positions | Field value | Weighted sum | Check digit |
|---|---|---|---|---|
| Document number | 1–9 → 10 | L898902C3 | 316 | 6 |
| Date of birth | 14–19 → 20 | 740812 | 122 | 2 |
| Date of expiry | 22–27 → 28 | 120415 | 49 | 9 |
| Optional data | 29–42 → 43 | ZE184226B<<<<< | 401 | 1 |
| Composite | 1–10, 14–20, 22–43 → 44 | (combined) | 880 | 0 |
Character values: < = 0, A = 10, B = 11 … Z = 35. The specimen data is the ICAO Doc 9303 sample for the fictional state Utopia.
What is Passport MRZ Check Digit Calculator?
A Passport MRZ Check Digit Calculator is a tool that computes or verifies the check digits in the machine-readable zone of a passport (TD3 format). The TD3 MRZ has 2 lines of 44 characters.
Border control readers and airline systems reject a passport scan when any check digit fails, which catches OCR misreads and tampered fields.
What are the uses of Passport MRZ Check Digit Calculator?
There are 4 main uses of the Passport MRZ Check Digit Calculator, including OCR verification, airline check-in, and identity verification apps.
- OCR verification: Document readers confirm MRZ reads with the 5 check digits.
- Airline check-in: Check-in systems validate passport data for Advance Passenger Information (API).
- Identity verification apps: KYC apps check MRZ data before NFC chip reading.
- Specimen testing: Developers test parsers with the ICAO sample passport.