Body Mass Index (BMI) Regex for PHP

What this pattern does

This page provides a well-structured, multi-part regular expression for matching body mass index (bmi), ported and verified for PHP. Identity and credential patterns need both correctness and safety, since they're frequent targets for adversarial input. The snippet below is ready to drop into your PHP project — whether you're validating in a Laravel validator, a WordPress plugin, or a standalone PHP script.

Php Implementation

<?php
// Body Mass Index (BMI)
// ReDoS-safe | RegexVault — Identity & PII > Biometric & Physical

define('BODY_MASS_INDEX_BMI_PATTERN', '/^(?:(?:[1-6][0-9](?:\.[0-9]{1,2})?)|(?:70(?:\.0{1,2})?))$/');

function validate_body_mass_index_bmi(string $input): bool {
    return (bool) preg_match(BODY_MASS_INDEX_BMI_PATTERN, $input);
}

// Example
var_dump(validate_body_mass_index_bmi("22.5")); // bool(true)

Test Cases

When to use this pattern

This pattern is drawn from the Identity & PII > Biometric & Physical category and carries a ReDoS-safe certification. That matters for PHP developers because especially relevant in PHP where PCRE backtracking limits can trigger silent failures on malicious input. 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

Normal BMI range is 18.5-24.9. BMI is a derived health metric — stored in medical records, used in insurance underwriting. As a health data attribute, it falls under GDPR Article 9 sensitive data category when processed for medical purposes.