Unit Conversion Pitfalls Every Developer Should Know

Floating-Point in Conversion Math

IEEE 754 double-precision arithmetic causes rounding errors in seemingly simple conversions. 1 inch to cm: 1 × 2.54 = 2.54 (exact, because 2.54 is representable). 1/3 meter to cm: 100/3 = 33.333333333333336 (inexact, because 1/3 repeats in binary). Always round results to a reasonable precision — 10 significant figures for engineering, 4 for everyday use. Never display unrounded raw floating-point output to users.

Temperature Is Special

Temperature conversions use both scaling and offset, not simple multiplication. T(°F) = T(°C) × 9/5 + 32. The zero points are different: 0°C = 32°F = 273.15K. Our converter handles all three scales correctly. Absolute zero (0 K = -273.15°C = -459.67°F) is a hard floor — no temperature conversion should produce a value below absolute zero.

Data Storage: Binary vs Decimal

Hard drive manufacturers use decimal units (1 GB = 1,000,000,000 bytes). Operating systems use binary units (1 GiB = 1,073,741,824 bytes). This is why a 500 GB drive shows as 465 GB in Windows. Our converter lets you choose binary or decimal prefixes so you can explain this discrepancy to users in your own applications.