UK Postcode (Full Format) Regex for Python

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching uk postcode (full format), 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

# UK Postcode (Full Format)
# ReDoS-safe | RegexVault — Localization > Postal Codes

import re

uk_postcode_full_format_pattern = re.compile(r'^(?:GIR\s*0AA$|[A-PR-UWYZ](?:[A-HK-Y][0-9][0-9A-HJKMNPR-VWY]?|[0-9][0-9A-HJKMNPR-VWY]?)\s[0-9][ABD-HJLNP-UW-Z]{2})$')

def validate_uk_postcode_full_format(value: str) -> bool:
    return bool(uk_postcode_full_format_pattern.fullmatch(value))

# Example
print(validate_uk_postcode_full_format("SW1A 1AA"))  # 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

Structure: area (1-2 letters) + district (1-2 alphanumeric) + space + sector (1 digit) + unit (2 letters). The inward code letters exclude C, I, K, M, O, V. GIR 0AA is the only postcode without a space.