Unit Converter: Frequently Asked Questions

All conversions use exact or highly precise conversion factors. Length conversions are exact (1 inch = 2.54 cm by definition). Temperature conversions are exact formulas. Results are shown to sufficient decimal places to be accurate for all practical purposes.

Mass is the amount of matter in an object (measured in kilograms). Weight is the force exerted by gravity on that mass (measured in newtons). In everyday use, we use the words interchangeably because we assume standard Earth gravity. The converter converts between mass units.

In SI (decimal) units, 1 GB = 1,000,000,000 bytes. In binary units, 1 GiB (gibibyte) = 1,073,741,824 bytes. Hard drive manufacturers use decimal; operating systems historically used binary. This is why a 1 TB hard drive shows as ~931 GB in Windows.

A nautical mile is exactly 1,852 metres, defined as one minute of arc of latitude along any meridian of Earth. It is used in aviation and maritime navigation because it corresponds directly to degrees of latitude, making chart calculations simpler.

Absolute zero is −273.15°C, −459.67°F, and 0 K (Kelvin). It is the theoretical lowest possible temperature, where all molecular motion stops. The Kelvin scale starts at absolute zero, making it the natural scale for scientific use.

Volume conversions cover cups, fluid ounces, tablespoons, teaspoons, litres, and millilitres — all the units you encounter in cooking. One US cup = 236.6 mL. One tablespoon = 14.79 mL. One teaspoon = 4.93 mL.