Implementing Accurate Unit Conversions: Handling Floating Point and Edge Cases

Implementing Accurate Unit Conversions: Handling Floating Point and Edge Cases I discovered floating-point precision issues the hard way when a user reported that 1 kilogram wasn't converting to 2.20462 pounds—it was showing 2.2046200000000003. "Close enough" doesn't work in unit conversion. Users expect exact values. The Fundamental Problem JavaScript stores numbers as 64-bit floating point (IEEE 754). This means: 0.1 + 0.2 // 0.30000000000000004 (not 0.3!) 1 / 3 * 3 // 0.9999999999999999 (not 1!) For unit conversions, this compounds: const kilos = 75 ; const pounds = kilos * 2.20462 ; console . log ( pounds ); // 165.3465000000001 (should be 165.3465) The user sees garbage. Your converter looks broken. Solution 1: Decimal Libraries The most reliable approach is using a decimal math library: const Decimal = require ( ' decimal.js ' ); function convertKgToPounds ( kg ) { return new Decimal ( kg ). times ( ' 2.20462 ' ). toNumber (); } convertKgToPounds ( 75 ); // 165.3465 (exact) Decim