Useful answers.
Clearly explained.

Convert42 is an independent collection of everyday conversion tools from Big42. It runs calculations on your device, with no account required.

One calculation engine

Each family uses a common base unit. We convert the input to the base, then to the target. Temperatures include offsets. Reference tables use the same engine. Definitions are based on NIST SP 811, NIST length definitions and NIST binary prefixes.

Precision without false certainty

Automatic display uses up to 10 significant digits. Decimal settings control display rounding, not measurement accuracy. Very small or large numbers use scientific notation. Calculations use JavaScript floating-point arithmetic, so they are not arbitrary-precision or certified metrology tools.

Definitions matter

International inch: 0.0254 meters. International pound: 0.45359237 kilograms. US liquid gallon: 231 cubic inches. Imperial gallon: 4.54609 liters. Mechanical horsepower: 550 foot-pounds-force per second. Metric horsepower: 75 kilogram-force meters per second.

Inch fractions round to the nearest 1/64. Feet-and-inches outputs are rounded separately. We exclude mass-to-volume conversions without a substance density, currency rates, and variable calendar months.

Corrections

If a result seems wrong, check the unit variant and rounding first. For important work, cross-check the source definition and original measurement. Convert42 is operated by Big42. For corrections, email mrbig42@big42group.com and include the units and result you checked.

Factors and local implementation reviewed 23 October 2026. Independent project; no endorsement by NIST.