Tool to check BBAN numbers. The BBAN (Basic Bank Account Number) checksum algorithm allows to check if a full bank account BBAN number is correct.
BBAN Number - dCode
Tag(s) : Checksum
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BBAN Number
BBAN number checker/validator
NB: Do not confuse with IBAN. This tool checks BBAN, for full IBAN numbers, dCode has a tool for that:
BBAN checksum calculator
Answers to Questions (FAQ)
What is a BBAN? (Definition)
A BBAN (Basic Bank Account Number) is a number identifying a bank account in a country. It is composed of 10 to 30 characters, depending on countries, these characters include bank codes (including the account number) and a checksum key.
Example: In France a BBAN/RIB has 23 characters: bank code (5 digits) + counter code (5 digits) + account number (11 digits and / or letters) + RIB key (2 digits between 01 and 97).
French BBAN number: 12345 12345 0123456789A 03
What is the difference between BBAN and IBAN?
How to check if a BBAN is false/fraudulent?
It is not possible to verify that a BBAN exists with certainty (that is to say, that there is indeed a bank that contains this bank account and that account is active, with money on it), indeed, only banks know their account numbers and associated RIBs and this data is a banking secret. On the other hand, it is possible to check that a RIB is technically valid (that is to say that it does not contain an error in its digits / characters) thanks to the control key which is integrated into the BBAN and which therefore allows a partial verification. If the validation fails, then the RIB is necessarily false/erroneous.
How to verify an BBAN number? (Validity check)
The algorithm for the validation calculator checks the BBAN key via a modulo 97:
Example: The bank number is: 12345 12345 0123456789A 03
Step 1: Remove the key BBAN code.
Example: The key is composed of the last 2 digits: 03. The rest of the calculation is done with 12345 12345 0123456789A 00.
Step 2: replace any letters by figures in the table
| A, J | 1 |
| B, K, S | 2 |
| C, L, T | 3 |
| D, M, U | 4 |
| E, N, V | 5 |
| F, O, W | 6 |
| G, P, X | 7 |
| H, Q, Y | 8 |
| I, R, Z | 9 |
Example: A=1, the BBAN becomes 12345123450123456789100
Step 3: Calculate the value of the result modulo 97, then subtract the result to 97.
Example: $ 12345123450123456789100 \mod 97 \equiv 94 $ and $ 97 - 94 = 3 $
The checksum key is therefore 03 (the key removed previously), the BBAN is valid.
Why the modulo 97?
Why 97? Because it is a prime number (the largest with 2 digits) that will minimize the errors.
Source code
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