ISO 7064 MOD 37-2 Calculator

How ISO 7064 MOD 37-2 Calculator Works?

The ISO 7064 MOD 37-2 Calculator works by converting each alphanumeric character to a value 0–35, running the pure-system recurrence with radix 2 and modulus 37, and mapping the result to one of 37 check characters. Value 36 is written as an asterisk (*).

1. 1Convert digits to 0–9 and letters A–Z to 10–35.
2. 2Set p = 0 and process characters from left to right.
3. 3Update p = ((p + value) × 2) mod 37 for each character.
4. 4Compute the check value c = (38 − p) mod 37.
5. 5Map c back through 0–9, A–Z, * to get the check character.

ISO 7064 MOD 37-2 Calculator Formula

The ISO 7064 MOD 37-2 formula is c = (38 − p) mod 37, with the check alphabet 0–9, A–Z, and *.

pᵢ = ((pᵢ₋₁ + v(aᵢ)) × 2) mod 37
c = (38 − pₙ) mod 37  →  0–9 A–Z *

• v(a) is the character value (A = 10 … Z = 35).
• c is the check value 0–36.

(0 + 16) × 2 mod 37 = 32
(32 + 1) × 2 mod 37 = 29
(29 + 2) × 2 mod 37 = 25
(25 + 3) × 2 mod 37 = 19
(19 + 4) × 2 mod 37 = 9
(9 + 8) × 2 mod 37 = 34
(34 + 9) × 2 mod 37 = 12
(12 + 6) × 2 mod 37 = 36
(36 + 5) × 2 mod 37 = 8
(8 + 4) × 2 mod 37 = 24
(24 + 3) × 2 mod 37 = 17
(17 + 2) × 2 mod 37 = 1
(1 + 1) × 2 mod 37 = 4
Check value = (37 + 1 − 4) mod 37 = 34
Check character = Y

ISO 7064 MOD 37-2 Calculator Conversion Table

The ISO 7064 MOD 37-2 conversion table shows character values and sample strings with computed check characters.

What is ISO 7064 MOD 37-2 Calculator?

An ISO 7064 MOD 37-2 Calculator is a tool that computes 1 alphanumeric check character for strings made of digits and capital letters. ISO/IEC 7064 defines MOD 37-2 as the single-character pure system for the 36-character alphabet.

The check character can be the symbol *, so systems that store the result must accept 37 output characters. The ISBT 128 standard for blood and tissue labelling uses MOD 37-2 for the check character of each Donation Identification Number.

What are the uses of ISO 7064 MOD 37-2 Calculator?

There are 3 main uses of the ISO 7064 MOD 37-2 Calculator, including asset tags, alphanumeric serials, and conformance tests.

• Alphanumeric serial numbers: Manufacturers protect serials that mix letters and digits.
• ISBT 128 donation labels: Blood banks print a MOD 37-2 check character beside each Donation Identification Number.
• Conformance testing: Developers match the ISO annex example G123489654321 → Y.