Units & Quantities
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 algebraic computation functions. It also supports dimensional analysis, as well as purely symbolic operations on quantities.
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
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
Quantities with Uncertainty »
Around — numbers or quantities with specified uncertainties
VectorAround ▪ MeanAround ▪ AroundReplace ▪ ...
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
NondimensionalizationTransform — convert an equation to dimensionless form
Mixed Units
MixedUnit — a mixed unit formed from a list of units (e.g. hours, minutes, seconds)
MixedMagnitude — list of magnitudes corresponding to the units in a mixed unit
Currency Units
CurrencyConvert — convert between currencies, using real-time data
User-Defined Units & Physical Quantities
IndependentUnit — represent an arbitrary user-specified unit (e.g. "foxes")
IndependentPhysicalQuantity — represent a user-specified physical quantity
IndependentUnitDimension — represent a user-specified independent dimension for units