IBAN Calculator

ISO two-letter code.
Enter the complete domestic BBAN without the country code or IBAN check digits.
Calculated IBAN
Electronic Format
Check Digits
Total Length
MOD-97 Remainder
Checksum calculation only. A mathematically valid IBAN does not prove that the BBAN follows the selected country’s banking structure, that the bank or account exists, that the account belongs to a particular person, or that it can receive payments. Confirm payment details with the receiving bank or account holder.

What This Tool Does

This IBAN calculator converts a domestic bank sort code (or bank code) and account number into the standardized International Bank Account Number (IBAN) format used for international transfers, and can also look up the corresponding BIC (SWIFT) code.

You can also use this Recurring Deposit Calculator.

How It’s Calculated

IBAN generation follows international standards: ISO 13616 defines each country’s IBAN structure, ISO 3166-1 supplies the two-letter country code, and ISO 7064 (MOD-97-10) generates the two check digits that let a bank catch a mistyped number before a payment is sent.

The check-digit method, in outline:

  1. Arrange the domestic account details (BBAN) in the exact positions defined by the country’s format.
  2. Move the country code and a placeholder “00” to the end of the string.
  3. Convert any letters to numbers (A=10, B=11, … Z=35).
  4. Treat the result as one long number, and calculate: Check Digits = 98 − (that number mod 97)

Illustrative example (demonstrating the mechanism only, not a real account’s IBAN): Suppose a rearranged, letter-converted number works out to a value that leaves a remainder of 55 when divided by 97. The check digits would be 98 − 55 = 43. A correctly generated IBAN, when the full string (including its check digits) is run back through the MOD-97 test, will always leave a remainder of exactly 1 — that’s what confirms the checksum is internally consistent.

Edge Cases and Special Rules

  • A structurally valid IBAN doesn’t confirm the account is open: Passing the format and checksum checks only confirms the number is correctly constructed — it says nothing about whether the account actually exists or is active.
  • Many countries embed their own domestic check digit too: Separate from the IBAN-level MOD-97 check, the underlying domestic account number often has its own national checksum — France uses a MOD-97 RIB key, Spain uses two control digits, Italy a CIN character, and methods vary further by country and sometimes by bank. This is validated independently of the IBAN check.
  • Short account numbers are typically zero-padded, not left short: If an account number is shorter than the country’s expected length, it’s usually padded with leading zeros to fit the standard format.
  • Not every country uses IBAN: The United States, for example, doesn’t use the IBAN system at all, relying instead on routing numbers and account numbers for domestic and international transfers.

IBAN Validity vs. SEPA Reachability

These answer two different questions. Confirming an IBAN is valid means the number’s format and checksum are correct. Confirming SEPA reachability means the receiving bank actually supports the specific payment scheme you intend to use, such as a standard SEPA Credit Transfer or the faster SEPA Instant option. A perfectly valid IBAN can still belong to a bank that doesn’t support the particular scheme a payment is being sent through, which is why checking reachability separately matters for time-sensitive transfers.

Who Uses This

  • Individuals and businesses setting up or verifying international bank transfers
  • Companies validating customer-supplied bank details before processing payments
  • Accounting and finance teams double-checking payment details to avoid failed international transfers
  • Anyone converting a domestic UK sort code and account number into IBAN format for an overseas payment

IBAN vs. BIC/SWIFT Code

These are often needed together but identify different things. The IBAN identifies a specific account, effectively an address for the account itself, standardized across countries. The BIC (SWIFT code) identifies the bank and branch, an address for the institution handling the account, not the account itself. International transfers commonly require both: the IBAN to route funds to the right account, and the BIC to route the payment to the right bank.

FAQ

What is an IBAN?

A standardized International Bank Account Number that reformats a domestic account number and bank code into a structure recognized internationally for cross-border transfers.

How is the IBAN check digit calculated?

Using the ISO 7064 MOD-97-10 method, rearranging the account details, converting letters to numbers, and calculating 98 minus the remainder when divided by 97.

Does a valid IBAN guarantee the account is active?

No, it only confirms the number’s format and checksum are correct, not that the account is open or reachable.

What’s the difference between IBAN and BIC/SWIFT code?

IBAN identifies the specific account; BIC identifies the bank and branch, international transfers often need both.

Do all countries use IBAN?

No, some countries, including the United States, don’t use the IBAN system at all.

Try It Above

Select your country and enter your domestic bank code and account number in the IBAN calculator above to get the converted IBAN and corresponding BIC. Always double-check the result against your bank statement before using it for a transfer.