Swedish Postnummer Regex for Python

What this pattern does

This page provides a well-structured, multi-part regular expression for matching swedish postnummer, ported and verified for Python. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. The snippet below is ready to drop into your Python project — whether you're validating in a Django view, a FastAPI endpoint, or a standalone data processing script.

Python Implementation

# Swedish Postnummer
# ReDoS-safe | RegexVault — Localization > Postal Codes

import re

swedish_postnummer_pattern = re.compile(r'^(1[0-9]|[2-9][0-9])[0-9]\s?[0-9]{2}$')

def validate_swedish_postnummer(value: str) -> bool:
    return bool(swedish_postnummer_pattern.fullmatch(value))

# Example
print(validate_swedish_postnummer("11122"))  # True

Test Cases

When to use this pattern

This pattern is drawn from the Localization > Postal Codes category and carries a ReDoS-safe certification. That matters for Python developers because particularly important in Python web servers where CPU-bound regex operations can stall concurrent request handling. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

Swedish postcodes run from 10005 (Stockholm) to 98499 (Kiruna). The first digit ranges 1-9. The space after position 3 is conventional in display but not used in machine-readable contexts.