System Of Units

System Of Units

Saturday, December 21, 2024

Last Updated On

SI base units

Symbol

Name

Quantity

thermodynamic temperature

mol

SI defining constants

9192631770 Hz

speed of light

299792458 m/s

Plank constant

6.62607015*10^-34 J*s

elementary charge

1.602176634*10^-19 C

Boltzmann constant

1.380649*10^-23 J/K

Avogadro constant

6.02214076*10^-23 mol^-1

luminous efficacy of 540 THz light radiation

683 lm/W

hyperfine transition frequency of Cs

Symbol

Defining constant

Exact value

SI base units

Unit name

Unit symbol

Quantity name

Definition

second

time

The duration of 9192631770 periods of radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium-133 atom.

meter

length

The distance traveled by light in vacuum in 1/299792458 second

kilogram

mass

The kilogram is defined by setting the Planks constant h to 6.62607015*10^-34 J*s (J=kg*m^2*s^-2), given the definitions of the meter and the second.

ampere

electric current

The flow of 1/1.602176634*10^-19 times the elementary charge e per second, which is approximately 6.2415090744*10^18 elementary charges per second.

kelvin

thermdynamic temperature

The Kelvin is defined setting the fixed numerical value of the Boltsmann constant k to 1.380649*10^-23 J*K^-1, (J=kg*m^2*s^-2), given the definition of the kilogram, the meter, and the second.

mole

mol

amount of substance

The amount of substance of 6.02214076*10^23 elementary entities. This number is the fixed numerical value of the Avogadro constant NA ,when expressed in the unit mol^-1

candela

luminous intensity

The luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 5.4*10^14 Hertz and that has a radiant intensity in that direction of 1/683 watt per steradian.

Derived SI base units

Name

Symbol

rad

°C

kat

Kcd

ΔνCs

Quantity

energy, work, heat

electric potential, voltage, emf

capacitance

resistance, impedance, reactance

electrical conductance

magnetic flux

magnetic flux density

radionuclide decay per unit time

absorbed dose ionizing radiation

equivalent dose ionizing radiation

catalytic activity

In SI base units

m/m

In Other SI units

m^2/m^2

s^-1

kg*m*s^-1

N/m^2 = J/m^3

kg*m^-1*s^-2

N*m = J*m^3

kg*m^2*s^-2

N*m = Pa*m^3

kg*m^2*s^-3

J/s

s*A

kg*m^2*s^-3*A^-1

W/A = J/C

kg^-1*m^-2*s^4*A^2

C/V = C^2/J

kg*m^2*s^-3*A^-2

V/A = J*s/C^2

kg^-1*m^-2*s^-3*A^2

Ω^-1

kg*m^2*s^-2*A^-1

V*s

kg*s^-2*A^-1

Wb/m^2

kg*m^2*s^-2*A^-2

Wb/A

°C = K-273.15

cd*m^2/m^2

cd*sr

cd*m^2/m^4

lm/m^2 = cd*sr*m^-2

s^-1

m^2*s^-2

J/kg

m^2*s^-2

J/kg

mol*s^-1

Coherent derived SI base units

Name

Symbol

Quantity

In SI base units

m^2

m^3

m/s

meter per second squared

m/s^2

acceleration

reciprocal meter

m^-1

wavenumber, vergence

kilogram per cubic meter

kg/m^3

density

kilogram per square meter

kg/m^2

surface density

cubic meter per kilogram

m^3/kg

specific volume

ampere per square meter

A/m^2

current density

ampere per meter

A/m

magnetic field strength

mole per cubic meter

mol/m^3

concentration

kilogram per cubic meter

kg/m^3

mass concentration

candela per square meter

cd/m^2

Pa*s

N*m

N/m

rad/s

angular velocity, angular frequency

radian per second squared

rad/s^2

angular acceleration

watt per square meter

W/m^2

heat flux density, irradiance

joule per kelvin

J/K

entropy, heat capacity

joule per kilogram kelvin

J/(kg*K)

specific heat capacity, specific entropy

joule per kilogram

J/kg

specific energy

watt per meter kelvin

W/(m*K)

thermal conductivity

joule per cubic meter

J/m^3

energy density

volt per meter

V/m

electric field strength

coulomb per cubic meter

C/m^3

electric charge density

m^-1*kg*s^-1

m^2*kg*s^-2

kg*s^-2

s^-1

s^-2

kg*s^-3

m^2*kg*s^-2*K^-1

m^2*s^-2*K^-1

m^2*s^-2

m*kg*s^-3*K^-1

m^-1*kg*s^-2

m*kg*s^-3*A^-1

m^-3*s*A

coulomb per square meter

C/m^2

surface charge density, electric flux density, electric displacement

farad per meter

F/m

permittivity

m^-2*s*A

m^-3*kg^-1*s^4*A^2

H/m

J/mol

m*kg*s^-2*A^-2

m^2*kg*s^-2*mol^-1

joule per mole kelvin

J/(mole*K)

molar entropy, molar heat capacity

coulomb per kilogram

C/kg

exposure (alpha and gamma rays)

m^2*kg*s^-2*K^-1*mol^-1

kg^-1*s*A

Gy/s

W/sr

m^2*s^-3

m^2*kg*s^-3

watt per square meter steradian

W/(m^2*sr)

radiance

katal per cubic meter

kat/m^3

catalytic activity concentration

kg*s^-3

m^-3*s^-1*mol

SI prefixes

Prefix

Name

Symbol

quetta

Base

10^30

Decimal

1000000000000000000000000000000

ronna

10^27

1000000000000000000000000000

yotta

10^24

1000000000000000000000000

zetta

10^21

1000000000000000000000

exa

10^18

1000000000000000000

peta

10^15

1000000000000000

tera

10^12

1000000000000

giga

10^9

1000000000

mega

10^6

1000000

kilo

10^3

1000

hecto

10^2

100

deca

10^1

10^0

deci

10^-1

0.1

centi

10^-2

0.01

milli

10^-3

0.001

micro

10^-6

0.000001

nano

10^-9

0.000000001

pico

10^-12

0.000000000001

femto

10^-15

0.000000000000001

atto

10^-18

0.000000000000000001

zepto

10^-21

0.000000000000000000001

yocto

10^-24

0.000000000000000000000001

ronto

10^-27

0.000000000000000000000000001

quecto

10^-30

0.000000000000000000000000000001

Non-SI Units

Linear measure

Unit

Symbol

SI equivalent

inch

in, "

0.0254 m

yard

0.9144 m

mile

1609.3 m

Survey measure

Unit

Symbol

SI equivalent

link

0.2011 m

survey foot

0.30480061 m

yard

0.9144 m

rod, pole, perch

5.029 m

foot

ft, '

0.3048 m

chain

20.117 m

furlong

fur

201.17 m

US Statute mile

1609.3 m

Area

Unit

Symbol

SI equivalent

Square foot

sq ft

0.09290 m^2

Square yard

sq yd

0.8361 m^2

Square rod

sq rd

25.29 m^2

Acre

acre

4036 m^2

Square mile

sq mi

2590000 m^2

Township

93240000 m^2

Volume (Dry)

Unit

Symbol

SI equivalent

Cubic inch

in^3

0.00001638 m^3

Cubic foot

ft^3

0.02831 m^3

Cubic yard

yd^3

0.7646 m^3

0.0005506 m^3

0.001101 m^3

0.00881 m^3

0.03424 m^3

Volume (Liquid)

Unit

Symbol

SI equivalent

Gallon

gal

0.003785 m^3

Quart

0.009464 m^3

Pint

0.004732 m^3

Fluid ounce

fl oz

0.00002957 m^3

Fluid dram

fl dr

0.000003696 m^3

Minim

mini

0.000000616 m^3

Mass

Unit

Symbol

SI equivalent

Ounce

0.02835 kg

Pound

0.4536 kg

Ton

ton

907.2 kg

Troy ounce

oz t

0.0311 kg

Liter

0.001 m^3

Unusual Units Of Measure

Unit Name

SI Equivalent

0.00508 m

0.01905 m

0.04445 m

0.1016 m

0.299792458 m

0.3 m

2.4 m

19 m

9.1 m long, 49 m wide

80 m

6371000 m

384400000 m

149600000000000000 m

1.2 m

10^-28 m^2

9.29 m^2

0.00003 m^3

0.000025 m^3

23.6 m^3

1.1 m^3

3.62 m^3

1.1 m^3

51 kg

1.89813*10^27 kg

1.9884*10^30 kg

Time

Unit

Symbol

SI equivalent

second

1 s

minute

min

60 s

3600 s

86400 s

2629746 s

31556952 s

315569520 s

cen

3155695200 s

Fahrenheit

°F = -459.67+(1.8*K)