Generate test BSN numbers
Fictional numbers with correct check digits, for testing software. They may by chance match a real person's number, so never use them to identify or impersonate anyone.
Click a number to copy it.
How a BSN is structured
- 9 digits (older numbers may be written with 8, leaving out a leading zero).
- No meaning in the digits: no birth date, sex or region.
- The whole number must pass the elfproef.
How the check works
Using the published example 111222333:
Multiply the digits by 9, 8, 7, 6, 5, 4, 3, 2 and −1: 1×9 + 1×8 + 1×7 + 2×6 + 2×5 + 2×4 + 3×3 + 3×2 + 3×(−1) = 66. 66 is divisible by 11 (66 = 11 × 6), so the number passes the elfproef.
A passing check only means the number is well-formed; it doesn't prove the number was issued to anyone.
Finding BSN numbers in text? The EU PII Redaction API finds and replaces national ID numbers from 21 EU/EEA countries, plus names, IBANs, emails and phones, in free text: for example before sending customer messages to an LLM. Free plan available; Python package and MCP server on GitHub.
Frequently asked questions
Is the elfproef enough to prove a BSN is real?
No. Roughly 1 in 11 random 9-digit numbers pass it. It catches typos, not made-up numbers.
Is a BSN the same as the old sofinummer?
Yes. The BSN replaced the sofinummer in 2007 and kept the same numbers.