Glossary
Table G1 Prefixes Used with Sl (Metric) Units 

Prefix  Factor  Symbol 
exa  1,000,000,000,000,000,000 = 10^{18}  E 
peta  1,000,000,000,000,000 = 10^{15}  P 
tera  1,000,000,000,000 = 10^{12}  T 
giga  1,000,000,000 = 10^{9}  G 
mega  1,000,000 = 10^{6}  M 
kilo  1,000 = 10^{3}  k 
hecto  100 = 10^{2}  h* 
deka  10 = 10^{1}  da* 
deci  0.1 = 10^{–1}  d* 
centi  0.01 = 10^{–2}  c* 
milli  0.001 = 10^{–3}  m 
micro  0.000001 = 10^{–6}  m 
nano  0.000000001 = 10^{–9}  n 
pico  0.000000000001 = 10^{–12}  p 
femto  0.000000000000001 = 10^{–15}  f 
atto  0.000000000000000001 = 10^{–18}  a 
*Avoid where practical. 


To convert Sl unit 
To U.S. conventional unit 
Multiply by 
Area 

square centimeters 
square inches 
0.155 
square meters 
square feet 
10.764 
square kilometers 
square miles 
0.3861 
hectares 
acres 
2.471 
Concentration 

micrograms per gram 
parts per million 
1 
milligrams per liter 
parts per million 
1 
Length 

centimeters 
inches 
0.3937 
meters 
feet 
3.281 
kilometers 
miles 
0.6214 
Mass 

grams 
ounces 
0.03527 
kilograms 
pounds 
2.2046 
kilograms 
ton 
0.00110 
Pressure 

pounds per square foot 
pascal 
0.000145 
Radiation 

becquerel 
curie 
2.7 ´ 10^{11} 
becquerel 
picocurie 
27.0 
gray 
rad 
100 
sievert 
rem 
100 
coulomb per kilogram 
roentgen 
3,876 
Temperature 

degrees Celsius 
degrees Fahrenheit 
1.8, then add 32 
Velocity 

meters per second 
miles per hour 
2.237 
Volume 

cubic meters 
cubic feet 
35.315 
liters 
gallons 
0.2642 