Unit conversion is defined by the International System of Units (SI), maintained by the Bureau International des Poids et Mesures (BIPM) in Sèvres, France. The BIPM defines seven base units (metre, kilogram, second, ampere, kelvin, mole, candela) and all other physical quantities are derived from combinations of those bases. Since the 2019 SI redefinition, every base unit is anchored to a fundamental physical constant with an exact numerical value — the speed of light for the metre, the Planck constant for the kilogram, the caesium-133 hyperfine transition for the second — making the conversion factors exact rather than empirically measured.

This has real implications for the conversion factors used in these tools. The conversion 1 kg = 2.20462 lb is not approximate; it derives from the exact definition 1 lb = 0.45359237 kg established by the International Yard and Pound Agreement of 1959 and codified into US law by the Mendenhall Order of 1893. The conversion 1 inch = 2.54 cm is exact by the same 1959 agreement. Every unit conversion on ScoutMyTool uses these exact factors — no rounding at the algorithm level.

The conversion cluster is organised into two broad families. Physical units covers length, weight/mass, volume, area, temperature, speed, pressure, energy, power, angle, and time — all derived from the SI base units. Data and other conversions covers file size (bytes, bits, common prefixes with both decimal SI and binary IEC 60027-2 conventions), computer number formats (binary, decimal, hexadecimal, octal, base64), and formatting utilities (case conversion, colour space conversion, encoding).

One quirk worth naming: file size prefixes. "1 MB" can mean 1,000,000 bytes (SI decimal, used by storage manufacturers, disk sizes advertised on retail packaging) or 1,048,576 bytes (binary, used by operating systems reporting available disk space, RAM). Our file-size converter offers both. The difference is significant — a "500 GB" drive holds about 465 GiB when reported by Windows.

Reviewed by the ScoutMyTool editorial team. All conversion factors sourced from NIST, BIPM, and IEC standards documents.