acalculator

Is this IBAN valid?

Paste an IBAN to check its country code, its length and its two check digits. Or type a country code and a domestic account number to make the check digits and the full IBAN.

Your numbers

I want to
Answer
Valid

Valid.

Valid
Yes
Right check digits
82
Print form
GB82 WEST 1234 5698 7654 32
Electronic form
GB82WEST12345698765432
Length for this country
22

Answer: Valid. Valid.

The results are estimates for information only. They are not financial, tax, or legal advice. Check the numbers with your lender or a qualified professional before you decide. Terms of use

How to calculate

Checks an IBAN: the country code, the length for that country, and the two MOD 97 check digits. Or works out the check digits and the full IBAN from a country code and a domestic account number.

Example with the default inputs (I want to Check an IBAN, IBAN GB82 WEST 1234 5698 7654 32): Valid.

Method: Check: the country code must use IBANs and the length must match the country; move the first four characters to the end, turn letters into numbers (A = 10 … Z = 35), and the whole number mod 97 must be 1. Make: check digits = 98 − (BBAN + country code + 00, letters as numbers) mod 97.

  • The page checks the country, the length and the check digits. It does not check each country’s own account format or whether the account exists.
  • Everything runs in your browser. The IBAN is not sent anywhere, but it is in the page link, so share links with care.

Machine-readable copies: Markdown, JSON.

Worked examples

Each example is checked against the calculator on every build.

  1. I want to Check an IBAN, IBAN GB82 WEST 1234 5698 7654 32 gives Answer Valid, Valid Yes, Right check digits 82, Length for this country 22, Electronic form GB82WEST12345698765432.Source: Wikipedia, "International Bank Account Number" (validation and check digit generation; example GB82 WEST 1234 5698 7654 32), https://en.wikipedia.org/wiki/International_Bank_Account_Number (retrieved 2026-10-05)
  2. I want to Check an IBAN, IBAN ie64ircE92050112345678 gives Answer Valid, Print form IE64 IRCE 9205 0112 3456 78.Source: Wikipedia, "International Bank Account Number" (validation and check digit generation; example GB82 WEST 1234 5698 7654 32), https://en.wikipedia.org/wiki/International_Bank_Account_Number (retrieved 2026-10-05) (example IE64 IRCE 9205 0112 3456 78)
  3. I want to Check an IBAN, IBAN GB82WEST12345698765433 gives Answer Not valid: the check digits should be 55, Valid No, Right check digits 55.Source: Wikipedia, "International Bank Account Number" (validation and check digit generation; example GB82 WEST 1234 5698 7654 32), https://en.wikipedia.org/wiki/International_Bank_Account_Number (retrieved 2026-10-05) (generation: 98 − remainder)
  4. I want to Make the check digits, Country code GB, Domestic account number (BBAN) WEST12345698765432 gives Answer GB82 WEST 1234 5698 7654 32, Right check digits 82.Source: Wikipedia, "International Bank Account Number" (validation and check digit generation; example GB82 WEST 1234 5698 7654 32), https://en.wikipedia.org/wiki/International_Bank_Account_Number (retrieved 2026-10-05)
  5. I want to Check an IBAN, IBAN GB82WEST1234569876543 gives Answer Not valid: a GB IBAN has 22 characters, this one has 21, Valid No.Source: Wikipedia, "International Bank Account Number" (validation and check digit generation; example GB82 WEST 1234 5698 7654 32), https://en.wikipedia.org/wiki/International_Bank_Account_Number (retrieved 2026-10-05) (United Kingdom: 22 characters)

How it works

An IBAN is a two-letter country code, two check digits, and the domestic account number (the BBAN). Spaces and hyphens are ignored, and small letters count as capitals.

Checking an IBAN

  1. The IBAN must start with two letters (the country code); if not, it is not valid. The country code must be one of the 89 that use IBANs, and the IBAN must have that country’s length (from the lengths table on the IBAN page cited below). If not, the IBAN is not valid.
  2. Move the first four characters (country code and check digits) to the end.
  3. Replace each letter with two digits: A = 10, B = 11, …, Z = 35.
  4. Read the result as one whole number and divide by 97. The IBAN is valid when the remainder is 1 and the check digits are from 02 to 98.

MOD 97-10 (ISO 7064, used by ISO 13616) only makes check digits from 02 to 98. So 00, 01 and 99 are never valid, even when the remainder is 1: GB01 WEST 0000 0000 0000 47 leaves 1, but the right check digits for that account number are 98.

When an IBAN fails, the page shows why: the country, the length, or the check digits (with the check digits that would be right for the rest of the IBAN).

Making the check digits

check digits = 98 − ((BBAN + country code + 00, letters as numbers) mod 97), written as two digits.

The BBAN must have the country’s length minus 4 characters.

Rules

  • Only the letters A to Z and the digits 0 to 9 count; any other character gives no answer.
  • The page does not check each country’s own BBAN format (which positions are letters or digits), the bank code, or whether the account exists.

Worked examples by hand

GB82 WEST 1234 5698 7654 32. GB IBANs have 22 characters; this has 22. Move GB82 to the end: WEST12345698765432GB82. Letters as numbers (W = 32, E = 14, S = 28, T = 29, G = 16, B = 11): 3214282912345698765432161182. This mod 97 = 1, so the IBAN is valid.

Making its check digits. WEST12345698765432 + GB + 00 → 3214282912345698765432161100. This mod 97 = 16, and 98 − 16 = 82, so the IBAN is GB82 WEST 1234 5698 7654 32.

One digit mistyped: GB82 WEST 1234 5698 7654 33. The length is right, but 3214282912345698765433161182 mod 97 = 28, not 1: not valid. The right check digits for this account number would be 98 − (3214282912345698765433161100 mod 97) = 98 − 43 = 55.

One character short: GB82 WEST 1234 5698 7654 3. It has 21 characters, not 22: not valid.

Other questions people ask

How do I check if an IBAN is valid?

Check that the country uses IBANs and that the IBAN has that country’s length (22 characters for the UK and Germany). Then move the first four characters to the end, turn each letter into a number (A = 10 up to Z = 35), and divide the whole number by 97. A valid IBAN leaves a remainder of 1, and its check digits are from 02 to 98.

How are the IBAN check digits worked out?

Write the domestic account number, then the country code, then 00. Turn letters into numbers (A = 10 … Z = 35), take the remainder of that number divided by 97, and subtract it from 98. Write the result as two digits: they go after the country code.

Does a valid IBAN mean the account exists?

No. The check digits only catch typing mistakes, such as one wrong digit or two digits swapped. An IBAN can pass every check and still not belong to any account. Confirm payment details with the person or the bank.

What does an IBAN look like?

Two letters for the country, two check digits, and then the domestic account number (the BBAN), up to 34 characters in all. On paper it is written in groups of four, such as GB82 WEST 1234 5698 7654 32; in electronic form it has no spaces.

Why does the length matter?

Each country fixes the length of its IBANs: 15 characters for Norway, 22 for Germany and the UK, 27 for France and Italy. A missing or extra character is caught by the length check before the check digits are tried.

Is my IBAN sent anywhere?

No. The page works it out in your browser. The IBAN is in the page’s link so that you can share an answer, so take care with whom you share that link.