US ZIP Code Regex for Python

What this pattern does

This page provides a well-structured, multi-part regular expression for matching us zip code, 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

# US ZIP Code
# ReDoS-safe | RegexVault — Localization > Postal Codes

import re

us_zip_code_pattern = re.compile(r'^([0-9]{5})(?:-([0-9]{4}))?$')

def validate_us_zip_code(value: str) -> bool:
    return bool(us_zip_code_pattern.fullmatch(value))

# Example
print(validate_us_zip_code("10001"))  # 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

Capture group 1: 5-digit ZIP, group 2: ZIP+4 extension. ZIP codes start from 00001 (Adjuntas, Puerto Rico) to 99950 (Ketchikan, Alaska). Ranges are not evenly distributed — 00001-00999 is Puerto Rico territory.