Converting Units of Measure:
Lesson
Topic Index | Grade 5 Math | Intermediate Test Prep | StudyZone

 

 

 
In problems which involve measurements such as width, length, height, weight, capacity or temperature, it is often necessary to convert from one measurement unit to another. 
For example, let's say you were going to purchase a new carpet for your bedroom. First you would get out your tape measure, or yardstick, and measure the length and width of the room.  This would probably be done in feet and inches.  Then you would take these measurements to the store and "OUCH" you see that all of the carpeting in the store is being sold by the "square yard!"  Being unable to convert the feet and inches measurements into square yards means that you  really don't know whether you are getting the best deal for your money. 
Hopefully after working through this lesson you will better understand how important this skill is, and how often this type of "math" gets into your everyday life.
 

 


Basic Conversion Rule:

To convert from a LARGER unit to a SMALLER unit...MULTIPLY

To convert from a SMALLER unit to a LARGER unit...DIVIDE
 

 


Complicating matters a bit is the fact that in the United States we have two different sets of measurement units.

Our basic system is the "customary" or "English" system.  In this system units include: inch, foot, yard, mile, ounce, pound, pint, quart, gallon and the Fahrenheit scale for temperature. 

 

However, as we do business in the global community,
the metric system is also a necessary system to understand. 
This system uses units such as: meter, centimeter, kilometer, gram, kilogram, liter, milliliter
and the Celsius scale for temperature.

In this lesson you will  see conversions in both of these systems.  However, this is NOT a lesson on either the English or Metric system, but rather this is an explanation of how to convert from one unit to another unit within the same system.
 

 



Let's start with an easy example.


The Pizza Shack uses 37 quarts of tomato sauce every day. 
How many gallons do they use?

Conversion factor:
1 gallon = 4 quarts
We are converting from a smaller unit (quart) to a larger unit (gallon). So we DIVIDE!
(37)/(4) = 9 with 1 quart left over.
37 quarts = 9 gal.1 qt.
 

  Let's try another..


4 boards measure; 21", 19", 33" and 43" respectively. If boards come in 8', 10', and 12' lengths, what length board should we buy so that the least scrap is left?

First we need to add the lengths of the boards together:
21 + 19 + 33 +43
116" total
Next we will convert the 8',10' and 12' lengths to inches.
We are converting from a larger unit to a smaller unit...so we must MULTIPLY.
Conversion factor: 1 foot = 12 inches
(8)(12) = 96
(10)(12) = 120
(12)(12) = 144
We need 116 total inches...so the best buy is the 10' (120") length.  There will only be 4 inches of scrap.
 

Now let's look at a metric conversion...


There are 720 centimeters of tape on a roll.  How many meters of tape is this?

Conversion factor: 1 meter = 100 centimeters
We are converting from a smaller unit to a large unit...so we must DIVIDE.
(720)/(100)
7.2
720 centimeters is the same as 7.2 meters!
 

 For some more practice on your own....

Click here  
(for English system)
Click here 
(for Metric system)