UnitConvert
UnitConvert[quantity, targetunit] converts a quantity to the target unit. UnitConvert[quantity] converts to SI base units.
Examples
Convert between units:
UnitConvert[Quantity[1, "Miles"], "Kilometers"]
(* Quantity[1.60934, "Kilometers"] *)
UnitConvert[Quantity[100, "Celsius"], "Fahrenheit"]
(* Quantity[212, "DegreesFahrenheit"] *)
(* To SI base units *)
UnitConvert[Quantity[1, "Horsepower"]]Please visit the official Wolfram Language Reference for more details.