A unit conversion changes the representation of a quantity without changing the quantity itself. Multiply by a factor equal to one, arranged so the source unit cancels and the target unit remains.
Conversion factors
One meter equals 100 centimeters, so meters can be converted to centimeters by multiplying by 100. Area and volume require squared or cubed factors: one square meter equals 10,000 square centimeters.
Temperature and data
Temperature uses offsets as well as scale factors, so a simple ratio is not enough. Data storage may use decimal units (1 KB = 1,000 bytes) or binary units (1 KiB = 1,024 bytes); state the convention.
Precision
Keep extra digits during the calculation and round only the final result. Browse the Conversion Calculators for length, weight, area, volume, speed, energy and more.