Measurement Guides
The definitions behind the converters, explained with worked examples and the mistakes that most often give a wrong answer.
Each guide covers one area where units are easy to get wrong: how the units are defined, how to convert them by hand, which version of a unit is meant where, and where common shortcuts go wrong. Every guide links to the converters that apply it.
All guides
- US and imperial units Why a gallon, a pint and a ton are different sizes in the US and the UK, which units the two systems share, and how to tell which one a recipe, fuel figure or label means.
- Stones and pounds How the stone works for body weight, how to convert between kilograms and stones and pounds by hand, and why 11.5 stone is not 11 stone 5 pounds.
- Temperature scales How the three temperature scales are defined, why converting between them needs an offset as well as a factor, and why a temperature difference converts differently from a reading.
- Speed units How the common speed units relate, where each is used, the exact factors behind them, and what a knot or an airspeed figure does and does not tell you.
- Horsepower and power Why there are several horsepowers, how to convert engine power between kilowatts and horsepower, and the difference between power and energy.
- Metric prefixes and data How SI prefixes scale units from nano to tera, why a 1 TB drive shows as about 931 GB, and how to turn internet speeds in bits into download sizes in bytes.
How UnitUtils converts
- Methodology The unit definitions, accepted input and rounding behind every converter.