Measurement and calculation guides
Understand units, conversion directions, source conventions and calculation checks before using a tool.
Choose the physical quantity first, then the unit. The guides explain the measurement basis; linked calculators perform the conversion in your browser.
How we check calculations and sources →
Length
13 distinct unit definitions and related conversion tools.
Area
10 distinct unit definitions and related conversion tools.
Volume
13 distinct unit definitions and related conversion tools.
Mass
9 distinct unit definitions and related conversion tools.
Time
8 distinct unit definitions and related conversion tools.
Temperature
4 distinct unit definitions and related conversion tools.
Velocity
7 distinct unit definitions and related conversion tools.
Pressure
13 distinct unit definitions and related conversion tools.
Energy
17 distinct unit definitions and related conversion tools.
Power
13 distinct unit definitions and related conversion tools.
Data
10 distinct unit definitions and related conversion tools.
Fuel Economy
5 distinct unit definitions and related conversion tools.
Force
13 distinct unit definitions and related conversion tools.
Torque
7 distinct unit definitions and related conversion tools.
Angle
6 distinct unit definitions and related conversion tools.
Data Rate
8 distinct unit definitions and related conversion tools.
Frequency
7 distinct unit definitions and related conversion tools.
Density
4 distinct unit definitions and related conversion tools.
Flow Rate
10 distinct unit definitions and related conversion tools.
Acceleration
4 distinct unit definitions and related conversion tools.
Electric current
7 distinct unit definitions and related conversion tools.
Voltage
7 distinct unit definitions and related conversion tools.
Electrical resistance
7 distinct unit definitions and related conversion tools.
Electrical conductance
6 distinct unit definitions and related conversion tools.
Electrical conductivity
6 distinct unit definitions and related conversion tools.
Capacitance
6 distinct unit definitions and related conversion tools.
Inductance
5 distinct unit definitions and related conversion tools.
Electric charge
9 distinct unit definitions and related conversion tools.
Electric field strength
5 distinct unit definitions and related conversion tools.
Electrical resistivity
4 distinct unit definitions and related conversion tools.
Magnetic flux
6 distinct unit definitions and related conversion tools.
Magnetic flux density
7 distinct unit definitions and related conversion tools.
Magnetic field strength
4 distinct unit definitions and related conversion tools.
Dynamic viscosity
4 distinct unit definitions and related conversion tools.
Kinematic viscosity
4 distinct unit definitions and related conversion tools.
Mass flow rate
6 distinct unit definitions and related conversion tools.
Absorbed radiation dose
6 distinct unit definitions and related conversion tools.
Equivalent radiation dose
6 distinct unit definitions and related conversion tools.
Radionuclide activity
9 distinct unit definitions and related conversion tools.
Absorbed radiation dose rate
5 distinct unit definitions and related conversion tools.
Heat capacity
5 distinct unit definitions and related conversion tools.
Specific heat capacity
4 distinct unit definitions and related conversion tools.
Thermal conductivity
4 distinct unit definitions and related conversion tools.
Thermal resistance
3 distinct unit definitions and related conversion tools.
Thermal insulance (R-value)
2 distinct unit definitions and related conversion tools.
Thermal diffusivity
4 distinct unit definitions and related conversion tools.
Heat flux density
5 distinct unit definitions and related conversion tools.
Surface tension
3 distinct unit definitions and related conversion tools.
Spectroscopic wavenumber
4 distinct unit definitions and related conversion tools.
Specific energy
5 distinct unit definitions and related conversion tools.
Volumetric energy density
4 distinct unit definitions and related conversion tools.
Photon radiation exposure
5 distinct unit definitions and related conversion tools.