Standard Prefixes
Prefix used in code Prefix for written unit Multiplier
da- deka- 10
h- hecto- 100
k- kilo- 1000
M- mega- 1e6
G- giga- 1e9
T- tera- 1e12
P- peta- 1e15
E- exa- 1e18
Z- zeta- 1e21
Y- yotta- 1e24

d- deci- 1e-1
c- centi- 1e-2
m- milli- 1e-3
mu- micro- 1e-6
n- nano- 1e-9
p- pico- 1e-12
f- femto- 1e-15
a- atto- 1e-18
z- zepto- 1e-21
y- yocto- 1e-24

Standard Units
Unit Symbol Definition Comments
Time
second sec 1 s
minute min 60 s
hour hr 60 min
hour hour 1 hr alternate symbol
hour h 1 hr alternate symbol
day day 24 hr
shake shake 10 ns
Hertz Hz 1 s^-1
Length or Distance
international foot ft 0.3048 m
inch in 1.0/12.0 ft
international mile mile 5280.0 ft
international mile mi 1 mile alternate symbol
milli-inch mil 0.001 in
Parsec pc 3.085678e16 m
League league 3 mile
Astronomical Unit ua 1.49598e11 m
Astronomical Unit AU 1.49598e11 m alternate symbol
yard yd 3 ft
Angstrom Ang 1e-10 m
Angstrom \\AA 1 Ang alternate symbol
furlong furlong 220 yd
fathom fathom 6 ft
Rod rd 16.5 ft
U.S. survey foot sft (1200./3937.) m
U.S. survey mile smi 5280 sft also called statue mile
point pt 1./72. in Typeface Point
pica pica 1./6. in Typeface Pica
Temperature
Celsius C 1 K -273.15
Rankine R 5.0/9.0 K
Fahrenheit F 1 R -459.67
Mass
gram g 0.001 kg This is case sensitive.
gram gm g (alternate symbol)
pound mass lbm 0.45359237 kg (avoirdupois)
Troy pound lbt 0.3732417 kg (apothecary)
carat (metric) carat 0.2 g
slug slug 1 lb sec^2/ft
snail snail 1 lb sec^2/in
Short Ton ton 2000 lbm
Long Ton ton_l 2240 lbm
Ounce oz 28.34952 g (avoirdupois)
Grain gr 64.79891 mg
Pennyweight dwt 1.55174 g
Force or Weight
Newton N 1 kg m/s^2
Dyne dyn 1e-5 N
pound force lb lbm G
pound force lbf lbm G
poundal poundal 1 lbm ft/sec^2
kilopound kip 1000 lbf
kilogram force kgf kg G
Energy
Joule J 1 N m
British Therm. Unit BTU 1055.056 J (International Table)
British Therm. Unit Btu 1 BTU alternate symbol
British Therm. Unit BTU_th 1054.350 J (Thermochemical)
calorie cal 4.1868 J (International Table)
calorie cal_th 4.184 J (Thermochemical)
Calorie Cal 4.1868 kJ (nutritionists)
electron volt eV 1.602177e-19 J
erg erg 1e-7 J
Ton of TNT TNT 4.184e9 J
Power
Watt W 1 J/s
Horse Power hp 550 ft lb/s
Pressure
bar bar 1e5 N/m^2
Pascal Pa 1 N/m^2
Pounds per sq. inch psi 1 lb/in^2
Pounds per sq. ft. psf 1 lb/ft^2
kilo psi ksi 1000.0 psi
atmospheres atm 1.01325e5 N/m^2
inches of Mercury inHg 3.387 kPa
millimeters Mercury mmHg 0.1333 kPa
Torr torr 1.333224 Pa
Volume or Area
Liter L 1/1000.0 m^3
gallon gal 3.785412 L
Pint (U.S. liquid) pint 1/8. gal
Quart (U.S. liquid) qt 2 pint
Pint (U.S. dry) dpint 0.5506105 L
Quart (U.S. dry) dqt 2 dpint
Acre acre 1/640.0 smi^2
Hectare ha 10000 m^2
Barrel (petroleum) barrel 158.9873 L
Fluid Ounce oz_fl 29.57353 mL
Gill (U.S.) gi 0.1182941 L
Peck (U.S.) pk 8.809768 L
Tablespoon tbl 1/32. pint
Teaspoon tsp 1/3. tbl
Cup cup 16. tbl
Electromagnetism
Coulomb Co 1 A s Electric Charge
Volt V 1 W/A Electric Potential
Ohm ohm 1 V/A Electric Resistance
Ohm \\Omega 1 V/A alternate symbol
Faraday faraday 96485.31 Co Electric Charge
Farad farad Co/V Capacitance
Stokes stokes 1e-4 m^2/s
Oersted Oe 79.57747 A/m
Webber Wb V s Magnetic flux
Tesla Tesla Wb/m^2 Magnetic flux density
Henry H Wb/A Inductance
Siemens S A/V Electrical Conductance
Light and Radiation
Lux lux cd/m^2 Iluminance
Lux lx cd/m^2
Lumen lm cd Luminous Flux
Stilb sb 10000 cd/m^2
Phot ph 10000 lx
Becquerel Bq s^-1 activity
Gray Gy J/kg Absorbed Dose, kerma
Sievert Sv J/kg Dose equivalent
Other Quantities
pound mole lbmole 1 mol lbm/g quantity
poise poise 1 g /sec cm viscosity
Gravity's accel. G 9.80665 m/sec^2 Gravity on Earth
Degree deg Pi/180 Can be used to convert from degrees to radians for trig functions.
Percent % 0.01
Knot knot 1852 m/hr velocity
Miles per Hour mph 1 mi/hr velocity
Gallon/minute gpm 1. gal/min flow rate
Revolution/minute rpm 360 deg/min