Base Units
Length
- meter (m)
- inch (in)
- foot (ft)
- yard (yd)
- mile (mi)
- link (li)
- rod (rd)
- chain (ch)
- angstrom
- mil
Surface Area
- m²
- sqin
- sqft
- sqyd
- sqmi
- sqrd
- sqch
- sqmil
- acre
- hectare
Volume
- m³
- litre (l, L, lt, liter)
- cc
- cuin
- cuft
- cuyd
- teaspoon
- tablespoon
Liquid Volume
- minim
- fluiddram (fldr)
- fluidounce (floz)
- gill (gi)
- cup (cp)
- pint (pt)
- quart (qt)
- gallon (gal)
- beerbarrel (bbl)
- oilbarrel (obl)
- hogshead
- drop (gtt)
Angles
- radian (rad)
- degree (deg)
- gradian (grad)
- cycle
- arcsecond (arcsec)
- arcminute (arcmin)
Time
- second (s, secs, seconds)
- minute (min, mins, minutes)
- hour (h, hr, hrs, hours)
- day (days)
- week (weeks)
- month (months)
- year (years)
- decade (decades)
- century (centuries)
- millennium (millennia)
Frequency
Mass
- gram (g)
- tonne
- ton
- grain (gr)
- dram (dr)
- ounce (oz)
- poundmass (lbm, lb, lbs)
- hundredweight (cwt)
- stick
- stone
Electric Current
Temperature
- kelvin (K)
- celsius (degC)
- fahrenheit (degF)
- rankine (degR)
Amount of Substance
Luminous Intensity
Force
- newton (N)
- dyne (dyn)
- poundforce (lbf)
- kip
Energy
- joule (J)
- erg
- Wh
- BTU
- electronvolt (eV)
Power
Pressure
- pascal (Pa)
- psi
- atm
- torr
- bar
Electricity and Magnetism
- ampere (A)
- coulomb (C)
- watt (W)
- volt (V)
- ohm
- farad (F)
- weber (Wb)
- tesla (T)
- henry (H)
- siemens (S)
- electronvolt (eV)
Binary
All time units are based on the Julian year, with one month being 1/12th of a Julian year, a year being one Julian year, a decade being 10 Julian years, a century being 100, and a millennium being 1000.
Prefixes
Decimal Prefixes
| Name | Abbreviation | Value |
|---|
| deca | da | 1e1 |
| hecto | h | 1e2 |
| kilo | k | 1e3 |
| mega | M | 1e6 |
| giga | G | 1e9 |
| tera | T | 1e12 |
| peta | P | 1e15 |
| exa | E | 1e18 |
| zetta | Z | 1e21 |
| yotta | Y | 1e24 |
| ronna | R | 1e27 |
| quetta | Q | 1e30 |
| deci | d | 1e-1 |
| centi | c | 1e-2 |
| milli | m | 1e-3 |
| micro | u | 1e-6 |
| nano | n | 1e-9 |
| pico | p | 1e-12 |
| femto | f | 1e-15 |
| atto | a | 1e-18 |
| zepto | z | 1e-21 |
| yocto | y | 1e-24 |
| ronto | r | 1e-27 |
| quecto | q | 1e-30 |
Binary Prefixes
| Name | Abbreviation | Value |
|---|
| kibi | Ki | 1024 |
| mebi | Mi | 1024² |
| gibi | Gi | 1024³ |
| tebi | Ti | 1024⁴ |
| pebi | Pi | 1024⁵ |
| exi | Ei | 1024⁶ |
| zebi | Zi | 1024⁷ |
| yobi | Yi | 1024⁸ |
Physical Constants
Universal Constants
| Name | Symbol | Value | Unit |
|---|
| speed of light | c | 299792458 | m · s⁻¹ |
| gravitation constant | G | 6.6738480e-11 | m³ · kg⁻¹ · s⁻² |
| planck constant | h | 6.626069311e-34 | J · s |
| reduced planck constant | ħ | 1.05457172647e-34 | J · s |
Electromagnetic Constants
| Name | Symbol | Value | Unit |
|---|
| magnetic constant | μ₀ | 1.2566370614e-6 | N · A⁻² |
| electric constant | ε₀ | 8.854187817e-12 | F · m⁻¹ |
| vacuum impedance | Z₀ | 376.730313461 | Ω |
| coulomb | κ | 8.9875517873681764e9 | N · m² · C⁻² |
| elementary charge | e | 1.60217656535e-19 | C |
| bohr magneton | μB | 9.2740096820e-24 | J · T⁻¹ |
| conductance quantum | G₀ | 7.748091734625e-5 | S |
| inverse conductance quantum | G₀⁻¹ | 12906.403721742 | Ω |
| magnetic flux quantum | φ₀ | 2.06783375846e-15 | Wb |
| nuclear magneton | μN | 5.0507835311e-27 | J · T⁻¹ |
| klitzing | Rᴋ | 25812.807443484 | Ω |
Atomic and Nuclear Constants
| Name | Symbol | Value | Unit |
|---|
| bohr radius | a₀ | 5.291772109217e-11 | m |
| classical electron radius | rₑ | 2.817940326727e-15 | m |
| electron mass | mₑ | 9.1093829140e-31 | kg |
| fermi coupling | Gₓ | 1.1663645e-5 | GeV⁻² |
| fine structure | α | 7.297352569824e-3 | - |
| hartree energy | Eₕ | 4.3597443419e-18 | J |
| proton mass | mₚ | 1.67262177774e-27 | kg |
| deuteron mass | mₓ | 3.3435830926e-27 | kg |
| neutron mass | mₙ | 1.6749271613e-27 | kg |
| quantum of circulation | ħ / (2mₑ) | 3.636947552024e-4 | m² · s⁻¹ |
| rydberg | R∞ | 10973731.56853955 | m⁻¹ |
| thomson cross section | | 6.65245873413e-29 | m² |
| weak mixing angle | | 0.222321 | - |
| efimov factor | | 22.7 | - |
Physico-Chemical Constants
| Name | Symbol | Value | Unit |
|---|
| atomic mass | mu | 1.66053892173e-27 | kg |
| avogadro | NA | 6.0221412927e23 | mol⁻¹ |
| boltzmann | k | 1.380648813e-23 | J · K⁻¹ |
| faraday | F | 96485.336521 | C · mol⁻¹ |
| first radiation | c₁ | 3.7417715317e-16 | W · m² |
| loschmidt | n₀ | 2.686780524e25 | m⁻³ |
| gas constant | R | 8.314462175 | J · K⁻¹ · mol⁻¹ |
| molar planck constant | NA · h | 3.990312717628e-10 | J · s · mol⁻¹ |
| molar volume | Vm | 2.241396820e-10 | m³ · mol⁻¹ |
| sackur tetrode | | -1.164870823 | - |
| second radiation | c₂ | 1.438777013e-2 | m · K |
| stefan boltzmann | σ | 5.67037321e-8 | W · m⁻² · K⁻⁴ |
| wien displacement | b | 2.897772126e-3 | m · K |
Adopted Values
| Name | Symbol | Value | Unit |
|---|
| molar mass | Mu | 1e-3 | kg · mol⁻¹ |
| molar mass of carbon-12 | M(¹²C) | 1.2e-2 | kg · mol⁻¹ |
| gravity | gₙ | 9.80665 | m · s⁻² |
| atm | atm | 101325 | Pa |
Natural Units
| Name | Symbol | Value | Unit |
|---|
| planck length | lP | 1.61619997e-35 | m |
| planck mass | mP | 2.1765113e-8 | kg |
| planck time | tP | 5.3910632e-44 | s |
| planck charge | qP | 1.87554595641e-18 | C |
| planck temperature | TP | 1.41683385e+32 | K |
The values of loschmidt and molar volume are at T = 273.15 K and p = 101.325 kPa. The value of sackur tetrode is at T = 1 K and p = 101.325 kPa.
Extended Units
| Name | SI |
|---|
| dBi | |
| dBm | |
| pixel / pixels | |
| megapixels / MP | 1e6 pixel |
| knot / knots / kn | 1.852 km/h |
| lux | |
| rpm | 6 deg/s |
