The CURP Validator checks whether a Mexican Clave Única de Registro de Población has the correct check digit, using RENAPO's official algorithm.
What it is
A CURP always has 18 fixed positions, and the last one is a check digit computed from the previous 17. A typo in any position changes the result of that calculation, and that's exactly what this tool detects.
Note: this validation checks only the mathematical structure of the number. It does not query RENAPO's database, so it can't confirm whether the CURP really belongs to someone or is active.
Who it's for
- Developers and QA validating Mexican user registrations.
- HR and admin teams quickly checking whether a CURP was typed correctly.
- Any system that needs a format check before accepting the value.
How the calculation works
Each character in the first 17 positions gets a value from 0 to 36 (digits and letters, including Ñ), multiplied by a weight descending from 18 to 2. Dividing the sum of those products by 10 gives a remainder; the expected check digit is 10 minus that remainder (or 0, if the remainder is 0). If it matches the typed 18th position, the CURP is valid.
How to use it
Paste the CURP into the field and click Validate. To generate valid test CURPs, use the CURP Generator.