Units
The Wolfram Language allows you to do arithmetic not only with symbols and numbers, but also with units. The Wolfram Language's integration with Wolfram|Alpha allows for a sophisticated unit system that combines the flexibility of free-form linguistics with the computational power of numerical and symbolic algorithms. The units framework integrates seamlessly with visualization, numeric, and symbolic functions.
Unit and Quantity Input
(
) — enter quantities and units, using free-form linguistics
Quantity — the value of a physical quantity with units included
QuantityArray — array of quantities with common units
QuantityDistribution — probability distribution with units
Quantity Components
QuantityMagnitude — give the value associated with a quantity
QuantityUnit — give the unit associated with a quantity
UnitDimensions — give the associated physical dimensions
IndependentUnit ▪ MixedUnit ▪ MixedMagnitude ▪ QuantityQ ▪ KnownUnitQ
Quantity Display
QuantityForm — display using the specified units or abbreviations
TargetUnits — target units to use for visualization and other functions
Unit Conversion
$UnitSystem — default unit system for output (e.g. "Imperial" or "Metric")
UnitConvert — convert between different units and unit systems
CompatibleUnitQ — test whether multiple quantities are compatible
CommonUnits — convert a list of quantities to a common unit
UnitSimplify — convert to simpler units
Physical Quantities
QuantityVariable — a variable representing a physical quantity (e.g. 
for mass)
QuantityVariableIdentifier ▪ QuantityVariablePhysicalQuantity
FormulaData — common scientific formulas involving physical quantities
Dimensional Analysis
DimensionalCombinations — possible combinations of dimensional physical quantities
QuantityVariableDimensions ▪ QuantityVariableCanonicalUnit
Currency Units
CurrencyConvert — convert between currencies, using real-time data