What is the format of a Danish IBAN?

A Danish IBAN is exactly 18 characters long. It begins with the country code DK, followed by 2 check digits, then a 4-digit bank registration number (Reg.nr.), a 9-digit account number, and finally 1 control digit embedded in the BBAN — all numeric after the two-letter prefix.

How does the MOD-97 checksum work?

The check digits at positions 3 and 4 are computed using ISO 7064 MOD-97-10. The algorithm moves the first four characters (country code + check digits) to the end of the string, replaces each letter with its numeric equivalent (A=10, B=11 … Z=35), and then divides the resulting large integer by 97. A valid IBAN always yields a remainder of exactly 1.

What is the Danish bank registration number (Reg.nr.)?

The 4-digit Reg.nr. (registreringsnummer) identifies the specific bank branch or financial institution. Danske Bank, for example, uses codes in the 0040 range. The Reg.nr. occupies positions 5 to 8 of the IBAN (the first four digits of the BBAN).

Can I use this tool to verify international transfers to Denmark?

Yes. Any SEPA credit transfer or wire transfer to a Danish bank account requires the recipient to supply a valid IBAN. This tool confirms the IBAN is structurally correct before you send the payment details, reducing the risk of a rejected or misdirected transfer.

Does a valid result mean the account exists?

No. A "valid" result means the IBAN is structurally and mathematically correct — the right length, a numeric BBAN, and a passing MOD-97 checksum. It does not confirm that the account is open, that it belongs to the person you expect, or that funds can be received. Only the recipient bank can confirm that.

Completely. The entire validation runs inside your browser using JavaScript. No IBAN or any other input is ever transmitted to a server. You can even disconnect from the internet after the page has loaded and the tool will still work.

Danish IBAN Validator

The Danish IBAN Validator lets you instantly verify any Danish bank account number in IBAN (International Bank Account Number) format. Paste the number, and the tool checks every structural rule defined in the ISO 13616 standard — country code, exact character count, numeric BBAN, and the ISO 7064 MOD-97-10 checksum — then breaks the result down so you can see exactly which part passed or failed. Everything runs in your browser; no data ever leaves your device.

How Danish IBANs are structured

A Danish IBAN is always exactly 18 characters long and follows this layout:

DK — the ISO 3166-1 alpha-2 country code for Denmark.
2 check digits — computed by the issuing bank using the MOD-97-10 algorithm so that any single transposition or substitution error is detected.
4-digit Reg.nr. (registreringsnummer) — identifies the bank branch or financial institution. Danske Bank typically uses codes starting with 0040; Nordea Denmark uses codes around 2000.
9-digit account number — uniquely identifies the individual account within that institution.
1 BBAN control digit — an additional integrity check on the national account number, bringing the total BBAN to 14 digits.

Together the BBAN occupies positions 5 to 18 (14 decimal digits), so the full IBAN looks like: DK50 0040 0440 1162 43.

How the MOD-97 checksum works

The ISO 7064 MOD-97-10 algorithm is the backbone of every IBAN checksum. To verify a Danish IBAN manually:

Strip spaces and uppercase everything.
Move the first four characters (DK50 for the example above) to the end, giving 004004401162 43DK50.
Replace each letter with its numeric equivalent: D becomes 13, K becomes 20, so DK50 becomes 13 20 50, yielding the digit string 00400440116243132050.
Divide that large number by 97. Because the number can be hundreds of digits long, divide progressively — take the first 9 digits, compute the remainder, prepend it to the next group, and repeat.
If the final remainder is exactly 1, the IBAN is valid.

This tool does all of that automatically and shows you the intermediate remainder alongside the pass/fail verdict.

Worked example

Consider the IBAN DK50 0040 0440 1162 43:

Part	Value	Meaning
Country	DK	Denmark
Check digits	50	MOD-97 check
Bank code	0040	Danske Bank
Account	044011624	Account number
BBAN control	3	Control digit

Rearranged digit string: 00400440116243132050 MOD-97 remainder: 1 — checksum passes.

The tool displays all of this in a structured table, and the formatted IBAN DK50 0040 0440 1162 43 can be copied with one click.

Danish IBANs are used across the SEPA Single Euro Payments Area, meaning they work seamlessly for euro transfers throughout the EU and EEA, as well as for domestic krone (DKK) payments inside Denmark. Always validate before initiating a cross-border transfer — a single digit error causes the payment to be rejected or, worse, credited to the wrong account.