How long is a Portuguese IBAN?

A Portuguese IBAN is exactly 25 characters: the country code PT, a two-digit check number, and a 21-digit BBAN (4-digit bank, 4-digit branch, 11-digit account, and 2 national check digits).

What is the MOD-97 check?

The IBAN check moves the first four characters (PT and the two check digits) to the end, converts letters to numbers (A=10 ... Z=35), and treats the result as one big integer. The IBAN is valid only if that integer modulo 97 equals 1.

Why is the prefix PT50 so common?

PT is Portugal's country code and 50 is simply the most frequently occurring check-digit pair for Portuguese accounts. The actual check digits depend on the specific account, so not every valid PT IBAN starts with 50.

Does a valid IBAN mean the account exists?

No. MOD-97 only confirms the IBAN is internally consistent and free of typos. It does not confirm the bank account is open or that it belongs to a particular person. Only the bank can confirm that.

Are spaces and lowercase allowed?

Yes. The tool strips spaces and uppercases the input before checking, so PT50 0002 0123... and pt5000020123... validate identically.

Portugal IBAN Validator

A Portuguese IBAN is the standardised account number used for SEPA payments, payroll, and direct debits in Portugal. Before sending money or saving a supplier’s bank details, you can confirm the IBAN is free of typos using the ISO 13616 MOD-97 check. This validator runs that check entirely in your browser.

How it works

A PT IBAN is 25 characters: PT + 2 check digits + a 21-digit BBAN. Validation follows the international MOD-97 rule:

Remove spaces and uppercase the input.
Confirm it starts with PT and is exactly 25 characters.
Move the first four characters (the PT and the two check digits) to the end.
Replace each letter with two digits: A = 10, B = 11, … Z = 35.
Interpret the whole string as one large integer and take it modulo 97.
The IBAN is valid only if the remainder is exactly 1.

Because the integer is huge, the tool computes the remainder digit-by-digit so it never overflows.

Example

For PT50 0002 0123 1234 5678 9015 4, the tool strips spaces to a 25-character string, rotates PT50 to the end, maps P = 25 and T = 29, and reduces the result modulo 97. A remainder of 1 means the IBAN passes; anything else means a digit is wrong.

Notes

A passing MOD-97 check confirms structure only — it does not confirm the account is open or owned by anyone in particular. Everything runs locally, so the IBAN never leaves your device.