CONCEPTS IN BIOLOGY
Appendix 1
The Metric System
Standard Metric Units 

Abbreviation 
Standard unit of mass 
gram 
g 
Standard unit of length 
meter 
m 
Standard unit of volume 
liter 
L 
Common Prefixes 
Examples 

kilo 
1,000 
A kilogram is 1,000 grams 
centi 
0.01 
A centimeter is 0.01 meter. 
milli 
0.001 
A milliliter is 0.001 liter. 
micro (μ) 
onemillionth 
A micrometer is 0.000001 (onemillionth) of a meter. 
nano (n) 
onebillionth 
A nanogram is 10^{9 }(onebillionth) of a gram. 
pico (p) 
onetrillionth 
A picogram is 10^{12 }(onetrillionth) of a gram. 
Units of Length
Unit 
Abbreviation 
Equivalent 
meter 
m 
approximately 39 in. 
centimeter 
cm 
10^{2} m 
millimeter 
mm 
10^{3} m 
micrometer 
μm 
10^{6} m 
nanometer 
nm 
10^{9} m 
angstrom 
A 
10^{10} m 
Length Conversions
1 in. = 2.5 cm
1 ft = 30 cm
1 yd = 0.9 m
1 mi = 1.6 km
1 mm = 0.039 in
1 cm = 0.39 in
1 m = 39 in
1 m = 1.094 yd
1 km = 0.6 mi
To Convert 
Multiply By 
To Obtain 
inches 
2.54 
centimeters 
feet 
30 
centimeters 
centimeters 
0.39 
inches 
millimeters 
0.039 
inches 
Units of Volume
Unit 
Abbreviation 
Equivalent 
liter 
L 
approximately 1.06 qt 
milliliter 
mL 
10^{3} L (1 mL = 1 cm^{3} = 1 cc) 
microliter 
μL 
10^{6} L 
Volume Conversions
1 tsp = 5 mL
1 tbsp = 15 mL
1 fl oz = 30 mL
1 cup = 0.24 L
1 pt = 0.47 L
1 qt = 0.95 L
1 gal = 3.8 L
1 mL = 0.03 fl oz
1 L = 2.1 pt
1 L = 1.06 qt
1 L = 0.26 gal
To Convert 
Multiply By 
To Obtain 
fluid ounces 
30 
milliliters 
quarts 
0.95 
liters 
milliliters 
0.03 
fluid ounces 
liters 
1.06 
quarts 
Units of Weight
Unit 
Abbreviation 
Equivalent 
kilogram 
kg 
10^{3} g (approximately 2.2 lb) 
gram 
g 
approximately 0.035 oz 
milligram 
mg 
10^{3} g 
microgram 
μg 
10^{6} g 
nanogram 
ng 
10^{9} g 
pictogram 
pg 
10^{12} g 
Weight Conversions
1 oz = 28.3 g
1 lb = 453.6 g
1 lb = 0.45 kg
1 g = 0.035 oz
1 kg = 2.2 lb
To Convert 
Multiply By 
To Obtain 
ounces 
28.3 
grams 
pounds 
453.6 
grams 
pounds 
0.45 
kilograms 
grams 
0.035 
ounces 
kilograms 
2.2 
pounds 
Temperature
Apothecary System of Weight and Volume*
Metric 
Apothecary 
Metric 
Apothecary 
Weight 
Weight 
Volume 
Volume 
30 g 
= 1 ounce 
1,000 mL 
= 1 quart 
15 g 
= 4 drams 
500 mL 
= 1 pint 
10 g 
= 2.5 drams 
250 mL 
= 8 fl ounces 
4 g 
= 60 grains 
90 mL 
= 3 fl ounces 

(= 1 dram) 
30 mL 
= 1 fl ounce 
2 g 
= 30 grains 


1 g 
= 15 grains 


___________________________
*Used by pharmacists in preparing medications.
Temperature Conversions
Some Equivalents
0°C = 32°F
37°C = 98.6°F
100°C = 212°F