Free tool
IBAN checker and calculator
Paste an IBAN and see straight away whether it is well formed and, if not, what is wrong. If you only have a 20-digit Spanish account number, work out its IBAN in the second tab. It covers the 89 countries in the SWIFT IBAN Registry, and for Spanish accounts it also checks the DC control digits of the old account number (CCC).
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With or without spaces, hyphens or the word IBAN in front.
Valid IBAN
- Country
- Spain (ES)
- Length
- 24 of 24
- IBAN check digits
- 91
- Account (BBAN)
- 21000418450200051332
Spanish account number (CCC)
- Bank code
- 2100
- Branch code
- 0418
- Control digits (DC)
- 45
- Account number
- 0200051332
DC correct: 4 checks the bank and branch codes, 5 checks the account number.
Everything is checked in your browser: the IBANs you type are not sent to any server or stored. A valid IBAN means the number is well built, not that the account exists.
Your IBAN on every invoice, payments reconciled
Save your IBAN once in Aikount and it appears on every invoice you issue. When bank movements come in, Aikount matches each payment to its invoice and only asks you about the unclear ones.
How to use it
- 1Paste the IBAN, with or without spaces, hyphens or the word IBAN in front.
- 2The result appears as you type: country, length, check digits and, for a Spanish IBAN, bank code, branch code, DC and account number. If something is wrong, you see the exact reason.
- 3To get the IBAN of a Spanish account, open "Work out IBAN from account" and type the 20 digits (bank code, branch code, DC and account number). If the DC is wrong, it tells you before giving you an IBAN.
- 4To check many at once (your suppliers' accounts before a batch of transfers, for example), use "Several at once": one per line, up to 500.
Examples
ES91 2100 0418 4502 0005 1332: valid
This is the sample IBAN that SWIFT publishes for Spain. Bank code (entidad) 2100, branch code (oficina) 0418, DC 45 and account number 0200051332. The 4 checks the bank and branch codes, the 5 checks the account number, and mod 97 leaves a remainder of 1.
ES91 2100 0418 4502 0005 1333: one digit copied wrong
Change only the last digit and both checks fail: mod 97 and the DC, which for that number would have to be 41.
2100 0418 4502 0005 1332: not an IBAN
These are the 20 digits of the old Spanish account number (CCC). It is missing ES and the check digits in front: ES91.
Working out the IBAN of 2310 0001 18 0000012345
The DC 18 matches the bank code, branch code and account. With the account followed by 142800, the remainder of dividing by 97 is 18, so the check digits are 98 - 18 = 80: ES80 2310 0001 1800 0001 2345.
A Spanish IBAN, piece by piece
The 20 digits after ES and the check digits are the old Spanish account number (CCC). Using the SWIFT sample IBAN ES91 2100 0418 4502 0005 1332:
| Digits | Part | What it is |
|---|---|---|
| ES | Country code | Spain. |
| 91 | IBAN check digits | Validate the whole IBAN (mod 97). |
| 2100 | Bank code (entidad) | Identifies the bank. The codes are assigned by the Banco de España. |
| 0418 | Branch code (oficina) | Identifies the branch of that bank. |
| 45 | Control digits (DC, dígitos de control) | The first checks the bank and branch codes, the second the account number. |
| 0200051332 | Account number (número de cuenta) | The account itself, 10 digits. |
How a Spanish IBAN is worked out from the account number
- Check the account DC. Each digit of "00" + bank code + branch code is multiplied by 1, 2, 4, 8, 5, 10, 9, 7, 3 and 6; add them up and subtract the remainder of dividing by 11 from 11 to get the first digit (11 becomes 0 and 10 becomes 1). The second digit comes the same way from the 10-digit account number.
- Append the country code and two zeros to the 20 digits: ES00. Letters become numbers (A = 10, B = 11... E = 14, S = 28), so you get the account followed by 142800.
- Divide that number by 97 and keep the remainder. The check digits are 98 minus that remainder, with a leading zero if there is only one digit.
- The IBAN is ES + those two digits + the 20 account digits. For 2100 0418 45 0200051332 the remainder is 7 and the check digits are 91: ES91 2100 0418 4502 0005 1332.
Your IBAN on every invoice, payments reconciled
In Aikount you add your IBAN to your company details and it is printed on every invoice PDF as the bank transfer payment method. When bank movements arrive, reconciliation links each payment to its invoice when the match is almost certain and leaves the rest as suggestions.
Create a free accountFrequently asked questions
How do I know if an IBAN is correct?
It starts with the country code, has the fixed length for that country (24 characters in Spain) and passes the check digit test, the mod 97 test of the ISO 13616 standard. Spanish accounts also carry the DC control digits. This tool checks all three.
Does a valid IBAN mean the account exists?
No, only that the number is well built. Whether it exists and who holds it is something only the bank knows. According to the Banco de España, since 9 October 2025 payment service providers must offer a free payee verification service: after you enter the IBAN and before the money is sent, your bank tells you whether the name you typed matches the account holder.
How do I work out an IBAN from a Spanish account number?
From the 20 digits of the Spanish account (CCC): append ES00, turned into 142800, divide by 97 and the IBAN check digits are 98 minus the remainder. The IBAN is ES + those two digits + the account. The "Work out IBAN from account" tab does it and checks the DC first.
Is the IBAN worked out here the one my bank gives me?
Yes, if the account number is typed correctly: a Spanish IBAN is always built the same way from the account, under ISO 13616. Still, for direct debits or payments, copy the IBAN from your online banking or a statement, which is the figure the bank stands behind.
How many characters does a Spanish IBAN have?
24: ES, 2 check digits and the 20 digits of the Spanish account number (CCC): 4 for the bank code (entidad), 4 for the branch code (oficina), 2 control digits (DC) and 10 for the account number.
What is the DC of a Spanish account?
Digits 9 and 10 of the account number (CCC). The first checks the bank and branch codes and the second checks the account number, using the weights 1, 2, 4, 8, 5, 10, 9, 7, 3 and 6 and mod 11.
Why doesn't it show the bank name?
We would have to match the bank code (the first four digits of the account) against the Banco de España register, and we don't want to show data we can't guarantee is up to date.
Official sources
Data checked on 28 October 2026.
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