Units of Measurement
The metric system is the most common system of measurement used throughout the world. In any
system of measurement, the basic units that are most commonly used are those of length, mass,
volume, temperature, and time. A comparison of these units in the English system (no longer used in
England) and their metric equivalents are given below.
Dimension
Definition
Metric Unit
English Unit
Equivalent
Length
Distance between
two points.
Meter (m)
Inch, foot,
yard, mile
1 yd = 0.917 m
1 in = 2.54 cm
Mass
Quantity of matter.
Gram (g)
Pound, ton
1 lb = 454 g
Volume
Amount of space
matter occupies.
Liter (L)
Pint, quart,
gallon
1 qt = 0.946 L
Temperature
Degree of hotness
or coldness.
Degree
Celsius
Degree
Fahrenheit.
F = 9/5 C + 32
Time
Period during which
an event occurs.
Second,
min., hour
Second, min.,
hour
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METRIC CONVERSIONS
One of the great advantages of using the metric system is that all units are based on a system of tens.
Instead of having several different units of mass, volume, and length as we have in the English system,
only one basic unit is used. These are the gram, the liter, and the meter. In order to indicate a fraction
or multiple of these units as is necessary when measuring small or large quantities, a system of prefixes
has been devised. Some prefixes are given below. Those bolded are ones most commonly used.
Prefix
Symbol
Fraction
Decimal
Meter Illustration
micro
u
1/1,000,000
0.000001
1,000,000 um = 1 m
milli
m
1/1,000
0.001
1,000 mm = 1 m
centi
c
1/100
0.01
100 cm = 1 m
deci
d
1/10
0.1
10 dm = 1 m
UNIT (gram, meter, liter)
deka
dk
10
10
1 dkm = 10 m
hecto
h
100
100
1 hm = 100 m
kilo
k
1000
1000
1 km = 1000 m
An advantage of using the metric system is that conversions within the system can easily be made by
simply shifting the position of the decimal point in the measurement. Using money as an example, if we
wished to know how many cents (notice cents = 1/100, and so the prefix centi-) there are in 5 dollars, we
would immediately answer 500. The unit dollar is changing from a large unit to the smaller unit of cents.
To maintain equivalence, the number 5, a small number, becomes larger, 500. This compensates for the
unit change of 100.
Unit becomes smaller
5 dollars = 500 cents
Number becomes larger
Units of Measurement
1
An equivalent problem in the metric system would be to change 5 meters to centimeters.
Unit becomes smaller
5 meters = 500 centimeters
Number becomes larger
The table below shows the number of places that the decimal point must be shifted for conversions
within the metric system.
kilo 1 km = 1000 m
Move decimal to left
hecto 10 hm = 1 km
deka 10 dkm = 1 hm
UNIT 10 m = 1 dkm
deci 10 dm = 1 m
centi 10 cm = 1 dm
Move decimal to right
milli 10 mm = 1 cm
To use this chart to make metric conversions, following these steps:
1. Locate the unit given and the unit sought in the diagram.
2. Determine the number of steps between the two units.
3. Determine whether the unit sought is larger or smaller than the unit given.
4. Determine whether the number will be smaller or larger than the one given. (If the unit
becomes larger, the number becomes smaller, and vice-versa.)
5. Move the decimal point to make the number larger or smaller according to the number of
steps between the units.
Problem: How many milliliters (mL) are equivalent to 5 liters (L)?
Solution: There are 3 steps between milliliter and liter. This indicates that the decimal place must be
moved 3 places. Because milliliter is a smaller unit in comparison to liters, therefore more milliliters are
needed, and the number before the unit will increase so the decimal point will be moved to make the
number larger.
5 L = ?? mL
(3 places or steps between units)
L [large]
mL [small]
5 L = 5,000 mL
(decimal moved 3 places to the right)
Problem: How many meters are equivalent to 750 centimeters?
Solution:
750.0 cm
cm [small]
750.0cm
=
?? m
(2 places or steps between units)
m [large]
=
7.50 m
(decimal moved 2 places to the left)
Units of Measurement
2
Exercises: Perform each of the following conversions.
1. 275. centimeters to meters
_______________
2. 453.5 grams to kilograms
_______________
3. 23. millimeters to centimeters
_______________
4. 568. millimeters to meters
_______________
5. 3.54 liters to milliliters
_______________
6. 76.4 kilograms to grams
_______________
7. 88.34 meters to millimeters
_______________
8. 0.01 liters to milliliters
_______________
9. 14.38 grams to milligrams
_______________
10. 0.0014 milliliters to liters
_______________
Answers: (1) 2.75 m, (2) 0.4535 kg, (3) 2.3 cm, (4) 0.568 m, (5) 3540 mL, (6) 76400 g,
(7) 88340 mm, (8) 10 mL, (9) 14380 mg, (10) 0.0000014 L
Units of Measurement
3