unit

schema/elements/unit/1.0.1/unit.schema.json

Defines physical measurement units as a string enum with 125+ supported unit categories, each corresponding to a physical dimension. Components that describe measured quantities (e.g., distances, temperatures, pressures) reference this element to specify their unit of measure.

The categories are organised by physical dimension:

Dimensionless and ratios

unit-dimensionless — quantities with no physical dimension
unit-non-dimensional — non-dimensional ratios and coefficients

Geometry and spatial

unit-length — linear distance (metres, feet, etc.)
unit-area — two-dimensional extent
unit-volume — three-dimensional extent
unit-reciprocal-length — inverse length (e.g., wavenumber)
unit-reciprocal-area — inverse area
unit-reciprocal-volume — inverse volume
unit-plane-angle — angles in a plane (degrees, radians, etc.)
unit-solid-angle — solid angles (steradians)
unit-angle-per-length — angular change per unit length
unit-angle-per-volume — angular change per unit volume
unit-length-per-temperature — thermal expansion coefficient (length)
unit-length-per-mass — length per unit mass
unit-length-per-pressure — length per unit pressure
unit-second-moment-of-area — second moment of area (moment of inertia of a cross-section)

Time and motion

unit-time — duration (seconds, hours, etc.)
unit-reciprocal-time — inverse time (frequency)
unit-length-per-time — velocity
unit-linear-acceleration — rate of change of velocity
unit-angular-velocity — rate of angular change
unit-angular-acceleration — rate of change of angular velocity
unit-time-per-length — slowness (inverse velocity)
unit-time-per-volume — time per unit volume
unit-time-per-mass — time per unit mass
unit-volume-per-rotation — displacement volume per revolution

Mass and density

unit-mass — quantity of matter (kilograms, pounds, etc.)
unit-reciprocal-mass — inverse mass
unit-reciprocal-mass-time — inverse mass-time product
unit-mass-per-length — linear density
unit-mass-per-area — areal density
unit-mass-per-volume — volumetric density
unit-mass-per-volume-per-length — density gradient
unit-mass-per-time — mass flow rate
unit-mass-per-time-per-area — mass flux
unit-mass-per-time-per-length — dynamic viscosity
unit-mass-per-energy — mass per unit energy
unit-mass-length — mass-length product (first moment of mass)
unit-mass-per-amount-of-substance — molar mass
unit-volume-per-mass — specific volume
unit-area-per-mass — mass absorption coefficient
unit-length-per-mass — length per unit mass

Force and pressure

unit-force — force (newtons, pounds-force, etc.)
unit-reciprocal-force — inverse force
unit-force-per-volume — body force density
unit-force-area — force-area product
unit-momentum — linear momentum
unit-reciprocal-pressure — compressibility
unit-pressure-squared — pressure squared
unit-pressure-per-volume — pressure gradient per volume
unit-pressure-time-per-volume — pressure-time per volume
unit-volume-per-pressure — volume per unit pressure
unit-length-per-pressure — length per unit pressure

Energy and power

unit-energy — energy (joules, calories, etc.)
unit-energy-per-time — power
unit-energy-per-mass — specific energy
unit-energy-per-mass-per-time — specific power
unit-energy-per-volume — energy density
unit-energy-per-area — energy per unit area
unit-molar-energy — energy per amount of substance
unit-moment-of-inertia — rotational inertia
unit-power-per-area — power flux (irradiance)
unit-power-per-volume — volumetric power density

Temperature and thermal

unit-thermodynamic-temperature — absolute temperature (kelvin, rankine)
unit-temperature-difference — temperature difference
unit-reciprocal-temperature — inverse temperature
unit-temperature-interval-per-length — temperature gradient
unit-temperature-interval-per-time — rate of temperature change
unit-temperature-interval-per-pressure — Joule–Thomson coefficient
unit-thermal-resistance — thermal resistance
unit-thermal-insulance — thermal insulance (R-value)
unit-thermal-conductance — thermal conductance
unit-thermal-conductivity — thermal conductivity
unit-specific-heat-capacity — specific heat capacity
unit-heat-capacity — heat capacity
unit-molar-heat-capacity — molar heat capacity
unit-heat-transfer-coefficient — convective heat transfer coefficient
unit-volumetric-heat-transfer-coefficient — volumetric heat transfer coefficient

Electrical and magnetic

unit-electric-current — electric current (amperes)
unit-electric-current-density — current per unit area
unit-electric-charge — electric charge (coulombs)
unit-electric-charge-per-area — surface charge density
unit-electric-charge-per-volume — volume charge density
unit-electric-charge-per-mass — charge-to-mass ratio
unit-electric-potential-difference — voltage (volts)
unit-reciprocal-electric-potential-difference — inverse voltage
unit-electric-resistance — electrical resistance (ohms)
unit-electric-resistance-per-length — resistance per unit length
unit-electrical-resistivity — electrical resistivity
unit-electric-conductance — electrical conductance (siemens)
unit-electric-conductivity — electrical conductivity
unit-electric-field-strength — electric field strength
unit-capacitance — capacitance (farads)
unit-permittivity — dielectric permittivity
unit-inductance — inductance (henries)
unit-magnetic-field-strength — magnetic field strength (H-field)
unit-magnetic-flux — magnetic flux (webers)
unit-magnetic-flux-density — magnetic flux density (teslas)
unit-magnetic-flux-density-per-length — magnetic flux density gradient
unit-magnetic-permeability — magnetic permeability
unit-magnetic-vector-potential — magnetic vector potential
unit-magnetic-dipole-moment — magnetic dipole moment
unit-electromagnetic-moment — electromagnetic moment
unit-dipole-moment — electric dipole moment
unit-reluctance — magnetic reluctance

Optical and photometric

unit-luminous-intensity — luminous intensity (candelas)
unit-luminance — luminance
unit-luminous-flux — luminous flux (lumens)
unit-illuminance — illuminance (lux)
unit-quantity-of-light — quantity of light (lumen-seconds)
unit-light-exposure — light exposure (lux-seconds)
unit-luminous-efficacy — luminous efficacy
unit-radiant-intensity — radiant intensity
unit-radiance — radiance

Chemistry and amount of substance

unit-amount-of-substance — amount of substance (moles)
unit-amount-of-substance-per-area — surface concentration
unit-amount-of-substance-per-volume — molar concentration
unit-amount-of-substance-per-time — molar flow rate
unit-amount-of-substance-per-time-per-area — molar flux
unit-area-per-amount-of-substance — molar area
unit-molar-volume — molar volume

Flow and volume rates

unit-volume-per-time — volumetric flow rate
unit-volume-per-time-per-time — rate of change of volumetric flow
unit-volume-per-time-length — volumetric flow per unit length
unit-volume-per-time-per-pressure — productivity index
unit-volume-per-time-per-pressure-length — transmissibility
unit-area-per-time — kinematic viscosity / diffusivity

Currency

unit-currency — monetary value

For the complete list of supported unit strings within each category, refer to the schema source.

Dimensionless and ratios​

Geometry and spatial​

Time and motion​

Mass and density​

Force and pressure​

Energy and power​

Temperature and thermal​

Electrical and magnetic​

Optical and photometric​

Chemistry and amount of substance​

Flow and volume rates​

Currency​