Common Units & Unit Prefixes
The following tables list all of the available unit prefixes, and many of the most
commonly used units in simulations at the NASA, Johnson Space Center - Engineering Branch.
Tables of units are provided for measuring time, length,
angle, mass, force, volt, current,
resistance, temperature, energy,
power, pressure, volume, and frequency.
Each of the rows in each of the tables contain a list of identifiers that refer to a
particular unit. Each of the identifiers in a list is synonymous. Also, characters
between brackets are optional. For example, "s", "second", "seconds" are treated as
being identical.
It is important to note that these tables are not complete lists of all available units.
If you're really curious, or if you just can't find the units you need, you could run
udunits2 -h
on the command line, follow the default database path listed at the bottom
of the help text, and examine the (fairly easy to read) UDUNITS2 xml database files.
You could also use udunits2
with the -H
option to determine whether the units you need exist, by guessing.
Unit Prefixes
Prefix |
Value |
Y, yotta |
1e24 |
Z, zetta |
1e21 |
E, exa |
1e18 |
P, peta |
1e15 |
T, tera |
1e12 |
G, giga |
1e9 |
M, mega |
1e6 |
k, kilo |
1e3 |
h, hecto |
100 |
da, deka |
10 |
d, deci |
0.1 |
c, centi |
0.01 |
m, milli |
1e-3 |
μ, u, 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 |
###Common Predefined Units
Time
Unit Identifier |
s, second[s] |
ms, millisecond[s] |
μs, microsecond[s] |
min, minute[s] |
h, hour[s] |
d, day[s] |
Length
Unit Identifier |
m, meter[s] |
au, astronomical_unit[s] |
nmile, nautical_mile[s] |
ft, foot, feet |
in, inch[es] |
yd, yard[s] |
mi, mile[s] |
km, kilometer[s] |
cm, centimeter[s] |
mm, millimeter[s] |
um, μm, micrometer[s] |
Angle
Unit Identifier |
rad, radian[s] |
°, degree[s] |
′, arcminute[s] |
″, arcsecond[s] |
Mass
Unit Identifier |
kg, kilogram[s] |
g, gram[s] |
lb, pound[s] |
slug, slug[s] |
NOTE: For Trick 13 and earlier, use 'sl' instead of 'slug'.
Force
Unit Identifier |
N, newton[s], kg.m/s^2, kg.m/s² |
lbf, pound[s]_force |
Voltage
Unit Identifier |
V, volt[s] |
mV, millivolt[s] |
uV, μV, microvolt[s] |
Current
Unit Identifier |
A, amp, ampere |
mA, milliamp |
uA, μA, microamp |
Resistance
Unit Identifier |
Ω, ohm[s] |
kΩ, kohm[s], kiloohm[s] |
MΩ, Mohm[s], megaohm[s] |
Temperature
Unit Identifier |
K, °K, degK |
°C, degC |
°F, degF |
°R, degR |
Energy
Unit Identifier |
J, joule[s] |
MJ, Mjoule[s], megajoule[s] |
W.h, watt.hour[s] |
kW.h, kilowatt.hour[s] |
BTU[s] |
Power
Unit Identifier |
W, watt |
kW, kilowatt |
MW, megawatt |
hp, horsepower |
Pressure
Unit Identifier |
Pa, pascal[s] |
psi |
atm, atmosphere |
mmHg, millimeter[s]_Hg |
inHg, inch[es]_Hg |
Volume
Unit Identifier |
l, liter |
cm³, cm^3, (cm)³ |
gallon |
oz |
Frequency
Unit Identifier |
Hz, hertz, 1/s |
kHz, kilohertz, kiloHz |
MHz, megahertz, megaHz |
Counting
Unit Identifier |
1 |
count[s] |
bit[s] |
byte[s] |