Open Source Tech Hub

Sep 14, 2026 · Backend Development

Why 0.1 + 0.2 ≠ 0.3 in PHP: Floating-Point Pitfalls and Correct Calculation Methods

This article explains why PHP's IEEE 754 floating-point arithmetic causes 0.1 + 0.2 ≠ 0.3, demonstrates integer overflow issues near PHP_INT_MAX, and details correct approaches: tolerance-based comparison, integer fixed-decimal scaling, and arbitrary-precision extensions BCMath and GMP with string inputs.