Convert between units of length, weight, temperature, volume, and speed
The United Kingdom uses a mixture of metric and imperial measurements in daily life, which can make conversions a frequent necessity. Road distances are measured in miles, but athletics tracks are in metres. Body weight might be discussed in stone and pounds, but food packaging uses grams and kilograms. Temperature is given in Celsius for weather forecasts, but some older references still use Fahrenheit. This unit converter supports five categories -- length, weight, temperature, volume, and speed -- covering the most common conversions you are likely to need. It handles both metric and imperial units, with correct conversions between systems. Temperature is treated as a special case because it uses offset formulas (not simple multiplication), which is why 0 degrees Celsius is 32 degrees Fahrenheit rather than 0.
To convert between units: 1. Select the unit you are converting from using the "From Unit" dropdown. Units are grouped by category (Length, Weight, Temperature, Volume, Speed) for easy browsing. 2. Select the unit you are converting to using the "To Unit" dropdown. Both units must be in the same category -- you cannot convert metres to kilograms, for example. 3. Enter the value you want to convert. The default is 1, which shows you the basic conversion factor between the two units. 4. View the result. The primary output shows the converted value rounded to 6 significant figures. The conversion formula shows the full equation, and the note provides context about the conversion method used. 5. If you select units from different categories (e.g., a length unit and a weight unit), the converter will display an informative message explaining that cross-category conversion is not possible.
For length, weight, volume, and speed, the converter uses a base-unit factor system. Each unit has a conversion factor relative to a base unit (metres for length, kilograms for weight, litres for volume, metres per second for speed). The conversion formula is: result = value x (fromFactor / toFactor), where each factor represents how many base units equal one of that unit. For example, to convert 5 miles to kilometres: 5 x (1609.344 / 1000) = 8.04672 km. The mile factor is 1609.344 (metres per mile) and the kilometre factor is 1000 (metres per kilometre). Temperature is the exception. Because temperature scales have different zero points, simple multiplication does not work. Instead, the converter first converts to Celsius (the intermediary), then from Celsius to the target unit. The formulas are: Fahrenheit to Celsius = (F - 32) x 5/9, Celsius to Fahrenheit = (C x 9/5) + 32, Celsius to Kelvin = C + 273.15, and Kelvin to Celsius = K - 273.15. These are combined for F-to-K and K-to-F conversions.