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[Technical Data]
SI (International System of Units) Excerpts from JIS Z 8203 (2000)

1. International System of Units (SI) and Usage
1-1. Scope of Application This standard specifies how to use the International System of Units (SI) and other international unitary systems,
as well as units used in correlation with units from international systems, and other units which may be used.
1-2. Terms and Definitions Terminology used in this specification and definitions thereof are as follows.
(1) International System of Units (SI) Coherent system of units adopted and recommended by the International Committee on Weights and Measures.
It contains base units and supplementary units, units derived from them and their integral exponents to the 10th power.
(2) SI Units Generic terms used to describe base units, supplementary units or derived units of the International System of Units (SI).
(3) Base Units Those units are given in Table 1.
(4) Supplementary Units Those supplementary units are given in Table 2.
Table 1. Base Units
Base Quantity Unit Symbol Definition
A meter is the length of the path traveled by light in a vacuum during a time interval
Length Meter m of of a second.
1
299 792 458
A kilogram is a unit of mass (neither weight nor force), it is equal to the mass of the
Mass Kilogram kg international prototype of the kilogram.
Second is the duration of 9 192 631 770 periods of the radiation corresponding to the
Time Second s transition between the two hyperfine levels of the ground state of the cesium-133 atom
An ampere is that constant current which, if maintained in two straight parallel conductors
Current Ampere A of infinite length, of negligible circular cross-section, and placed 1 meter apart in a vacuum,
would produce between these conductors a force equal to 2×10 Newton per meter of length.
−7
1
Thermodynamic Kelvin, a unit of thermodynamic temperature, is the fraction of the
Temperature Kelvin K thermodynamic temperature of the triple point of water. 273.16
Amount of Mole mol A mole is the amount of substance of a system that contains as many elementary
1
particles( ) or aggregation of elementary particles as there are atoms in 0.012 kilogram
Substance of carbon 12 and when the mole is used, the elementary particles must be specified.
A candela is the luminous intensity, in a given direction, of a source that emits
Luminance Candela cd monochromatic radiation of frequency 540×10 hertz and that has a radiant
12
1
Intensity intensity in that direction of watt per steradian.
683
1
Note( ) The elementary particles here must be atoms, molecules, ions, electrons or other particles.
Table 2. Supplementary Units
Base Quantity Unit Symbol Definition
A radian is the plane angle between two radii of a circle that subtend an arc whose
Plane Angle Radian rad
length is equal to the radius.
Solid Angle Steradian sr A steradian is the solid angle which, having its vertex in the center of a sphere, cuts off an area of the
surface of the sphere equal to that of a square with sides equal in length to the radius of the sphere.
(5) Derived Units The supplementary units are algebraically expressed using mathematical symbols such as plus, minus, etc.
The SI derived units with special names and symbols are given in Table 3.
Examples of SI Derived Units Expressed in Terms of Base Units Table 3. SI Derived Units with Special Names and Symbols
Base Quantity Base Quantity Expression in Terms of Base
Base Quantity Units or Supplementary
Name Symbol Base Quantity Units, Supplementary Units
Area Square meter m 2 Name Symbol or Other SI Units
Volume Cubic meter m 3 Frequency Hertz Hz 1Hz = s −1
Velocity Meter per second m/s Force Newton N 1N = 1 kg·m/s 2
Acceleration Meter per square second m/s 2 Pressure, Stress Pascal Pa 1Pa = 1 N/m 2
Wave Number Reciprocal meter m −1 Energy, Work, Heat Quantity Joule J 1J = 1 N·m
Density Kilogram per cubic meter kg/m 3 Work Rate, Process Rate, Power, Electric Power Watt W 1W = 1 J/s
Current Density Ampere per square meter A/m 2 Electric Charge, Quantity of Electricity Coulomb C 1C = 1 A·s
Magnetic Field Strength Ampere per meter A/m Electric Potential, Potential Difference, Voltage, Electromotive Force Volts V 1V = 1 J/C
Concentration (of Substance) Mole per cubic meter mol/m 3 Electrostatic Capacity, Capacitance Farad F 1F = 1 C/V
Specific Volume Cubic meter per kilogram m /kg Electric Resistance Ohm Ω 1Ω = 1 V/A
3
S
1S = 1 Ω
Siemens
Conductance
−1
Luminance Candela per square meter cd/m 2
Magnetic Flux Weber Wb 1Wb = 1 V·s
Magnetic Flux Density Tesla T 1T = 1 Wb/m 2
Inductance Henry H 1H = 1 Wb/A
Celsius Temperature Degree Celsius ˚C 1t˚C = (t+273.15)K
Luminous Flux Lumen lm 1lm = 1 cd·sr
Illuminance Lux lx 1lx = 1 lm/m 2
Radioactivity Becquerel Bq 1Bq = 1 s −1
B-003 Absorbed Dose Gray Gy 1Gy = 1 J/kg
1Sv = 1 J/kg
Dose Equivalent
Sievert
Sv