finance ToolUpdated 2026-09-20

IBAN Calculator & Checksum Validator

Prevent costly bank transfer delays and bounced wire fees. Verify the structural integrity and mathematical Mod-97 check digits of any International Bank Account Number (IBAN).

Formula & Mathematical Methodology

ISO 13616 Mod-97 Checksum: Rearranged Numeric String mod 97 === 1

Standard ISO 7064 / Mod-97-10 verification moves the country code and two check digits to the end, replaces all letters with numbers (A=10 through Z=35), and verifies that dividing the resulting integer by 97 produces a remainder of exactly 1.

Step-by-Step Worked Example

Scenario: Validate UK IBAN GB29NWBK60161331926819

1. Clean formatting: GB29NWBK60161331926819.

2. Move first 4 characters to the end: NWBK60161331926819GB29.

3. Convert letters to digits (N=23, W=32, B=11, K=20, G=16, B=11).

4. Form full numeric string: 2332112060161331926819161129.

5. Calculate Modulo 97: Remainder is exactly 1.

6. Result: Checksum validated successfully.

Final Calculated Result: Valid IBAN ✓ (Country: GB, Check: 29)

Frequently Asked Questions

Does this calculator verify that the bank account is currently active?

No, this calculator mathematically verifies that the IBAN conforms to ISO 13616 formatting and check-digit rules. Only the issuing financial institution can confirm whether an account is currently active.