DNI and NIE Letter Calculator — Spain
Find the control letter of a Spanish DNI or NIE number, or check that a full DNI, NIE or NIF is valid, using the official mod-23 rule.
Free, with no sign-up and no watermark. The file is processed in your browser and never uploaded.
Find the control letter of a Spanish DNI, NIE or K/L/M NIF, or check that a full ID with its letter is correct. The letter comes from the official mod-23 rule: divide the number by 23 and the remainder picks a letter from TRWAGMYFPDXBNJZSQVHLCKE.
For an NIE the leading X, Y or Z is first replaced by 0, 1 or 2.
Step by step
- Type the number: Enter 8 digits for a DNI, or X/Y/Z plus 7 digits for an NIE — with or without the final letter.
- Read the result: Without a letter you get the correct one; with a letter you’re told whether it matches.
Handy for
Forms and contracts
Check a DNI or NIE before it goes on an invoice, a rental contract or a job application.
Data entry
Catch a mistyped digit — almost any single wrong digit changes the letter.
Good to know
Company tax IDs (CIF, starting with A, B, …) use a different check and aren’t covered.
The letter confirms the number is well formed, not that the ID belongs to anyone.
Questions
Why is there no letter I, Ñ, O or U?
They were left out of the table to avoid confusion with similar-looking characters.
What are K, L and M NIFs?
Tax numbers for Spaniards under 14 without a DNI (K), Spanish residents abroad (L) and foreigners without an NIE (M). Their letter is worked out the same way as a DNI’s.
Is anything I type sent anywhere?
No. The calculation runs in your browser on your own device; nothing is uploaded or stored, and the page keeps working offline once it has loaded.
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