# Common units and conversions

You may also be interested in our units for magnetic properties page

## Temperature

Fahrenheit to Celsius: °C = (°F-32)/1.8

Celsius to Fahrenheit: °F = (1.8 × °C) + 32

Fahrenheit to Kelvin: convert °F to °C, then add 273.15

## Volume

1 liter (L) = 1.000 × 10–3 cubic meters (m3) = 61.02 cubic inches (in3)

## Mass

1 kilogram (kg) = 1000 grams (g) = 2.205 pounds (lb)

## Force

1 newton (N) = 0.2248 pounds (lb)

## Electric resistivity

1 micro-ohm-centimeter (µΩ·cm)
= 1.000 × 10–6 ohm-centimeter (Ω·cm)
= 1.000 × 10–8 ohm-meter (Ω·m)
= 6.015 ohm-circular mil per foot (Ω·circ mil/ft)

## Heat flow rate

1 watt (W) = 3.413 Btu/h

1 British thermal unit per hour (Btu/h) = 0.2930 W

### A note on SI

The values on this website are expressed in International System of Units, or SI (from the French Le Système International d’Unités). When possible, the common CGS or British equivalent has been parenthetically included as well.

These common conversions and constants have been included as a reference.

Please refer to NIST Special Publication 811 for further standards and conversions.

Ambler Thompson and Barry N. Taylor (2008), Guide for the Use of the International System of Units (SI) NIST Special Publication 811, 2008 Edition (version 3.2). [Online] Available: http://physics.nist.gov/SP811 [2023, Aug 3]. National Institute of Standards and Technology, Gaithersburg, MD.

The NIST Physical Constants webpage

## Length

centimeter (cm)meter (m)inch (in)
centimeter (cm)1 1.000 × 10-20.3937
meter (m)100139.37
inch (in)2.5402.540 × 10-21

1 micrometer (sometimes referred to as micron) = 10-6 m

1 mil = 10-3 in

## Area

cm2m2in2circ mil
cm21 10-40.15501.974 × 105
m2104115501.974 × 109
in26.4526.452 × 10-411.273 × 106
circ mil5.067 × 10-65.067 × 10–107.854 × 10-71

## Pressure

pascal (Pa)millibar (mbar)torr (Torr)atmosphere (atm)psi (lbf/in2)
pascal (Pa)1 1.000 × 10–27.501 × 10–39.868 × 10–61.450 × 10–4
millibar (mbar)1.000 × 10217.502 × 10–19.868 × 10–41.450 × 10–2
torr (Torr)1.333 × 1021.333 × 10011.316 × 10–31.934 × 10–2
atmosphere (atm)1.013 × 1051.013 × 1037.600 × 10211.470 × 101
psi (lbf/in2)6.897 × 1036.895 × 1015.172 × 1016.850 × 10–21
1 torr (Torr) =

133.332 pascal (Pa)
1.33 millibar (mbar)
0.001316 atmosphere (atm)
0.01934 psi (lbf/in2)

1 pascal (Pa) =

0.01 millibar (mbar)
0.007501 torr (Torr)
9.87 × 10–6 atmosphere (atm)
1.45 × 10–4 psi (lbf/in2)

## Magnetic induction B

gauss (G)kiloline/in2Wb/m2milligauss (mG)gamma (γ)
gauss (G)1 6.452 × 10–310–41000105
kiloline/in2155.011.550 × 10–21.550 × 1051.550 × 107
Wb/m210464.521107109
milligauss (mG)0.0016.452 × 10–610–71100
gamma (γ)10–56.452 × 10–810–90.011

1 ESU = 2.998 × 106 Wb/m2

## Magnetomotive force

abampere·turnampere·turnGilbert (Gi)
abampere·turn1 1012.57
ampere·turn0.111.257
Gilbert (Gi)7.958 × 10–20.79581

1 pragilbert = 4π ampere·turn

1 ESU = 2.655 × 10–11 ampere·turn

## Magnetic field strength H

abampere·turn/cm ampere·turn/cm ampere·turn/in ampere·turn/m oersted (Oe)
abampere·turn/cm 1 10 25.40 1000 12.57
ampere·turn/cm 0.1 1 2.540 100 1.257
ampere·turn/in 3.937 × 10–2 0.3937 1 39.37 0.4947
ampere·turn/m 0.001 0.01 2.540 × 10–2 1 1.257 × 10–2
oersted (Oe) 7.958 × 10–2 0.7958 2.021 79.58 1

1 Oe = 1 Gi

1 ESU = 2.655 × 10–9 ampere·turn/m

1 praoersted = 4π ampere·turn/m

## Energy, work, heat

Btu erg J cal kW·h
Btu 1 1.055 × 1010 1055 252.0 2.930 × 10–4
erg 9.481 × 10–11 1 10–7 2.389 × 10–8 2.778 × 10–14
J 9.481 × 10–4 107 1 0.2389 2.778 × 10–7
cal 3.968 × 10–3 4.186 × 107 4.186 1 1.163 × 10–6
kW·h 3413 3.6 × 1013 3.6 × 106 8.601 × 105 1

1 electronvolt (eV) = 1.602 × 10–19 joules (J)

## Fundamental physical constants

Symbol Value* Unit
speed of light in a vacuum c, c0 299 792 458 m · s–1
magnetic constant µ0 4π × 10–7 = 12.566 370 614... × 10–7 N · A–2
electric constant 1/µ0c2 ε0 8.854 187 817... × 10–12 F · m–1
characteristic impedance of
vacuum √µ0 /∈0 = µ0c
Z0 376.730 313 461...
Planck constant
in eV · s
h/2π
in eV · s
h 6.626 0693(11) × 10–34
4.135 667 43(35) × 10–15
1.054 571 68(18) × 10–34
6.582 119 15(56) × 10–16
J · s
eV · s
J · s
eV · s
elementary charge e 1.602 176 53(14) × 10–19 C
magnetic flux quantum h/2e Φ0 2.067 833 72(18) × 10–15 Wb
Avogadro constant NA, L 6.022 1415(10) × 1023 mol–1
atomic mass constant mu = ⅟₁₂m(12C) = 1 u mu 1.660 538 86(28) × 10–27 kg
Faraday constant NA e F 96 485.3383(83) C · mol–1
molar gas constant R 8.314 472(15) J · mol–1 · K–1
Boltzmann constant R/NA k 1.380 650 5(24) × 10–23 J · K–1
molar volume of ideal gas RT / p
T = 273.15 K, p = 101.325 kPa
T = 273.15 K, p = 100 kPa
Vm
22.413 996(39) × 10–3
22.710 981(40) × 10–3
m3 · mol–1
m3 · mol–1
Stefan-Boltzmann constant (π2/60)k4/h3c2 σ 5.670 400(40) × 10–8 W · m–2 · K–4
electron volt: (e/C) J eV 1.602 176 53(14) × 10–19 J
Bohr magneton eh/2me
in eV · T–1B/(J · T–1)](e/C)
µB 927.400 949(80) × 10–26
5.788 381 804(39) × 10–5
J · T–1
eV · T–1

*Values are shown in their concise form with uncertainty in parentheses. Numbers with uncertainty values are subject to revision. Refer to the NIST Reference on Constants, Units, and Uncertainty website for the latest values