Conversion Estimation
between Systems of Measure
Jen Kershaw
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Printed: December 12, 2014
AUTHOR
Jen Kershaw
www.ck12.org
C HAPTER
Chapter 1. Conversion Estimation between Systems of Measure
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Conversion Estimation
between Systems of Measure
Here you’ll learn to estimate equivalence between customary and metric units of measure.
Have you ever measured liquid?
Let’s say that you wanted to make a cake which needed 2 cups of milk. Could you estimate a conversion of two cups
of milk to liters?
This Concept will teach you how to estimate between customary and metric units of measurement.
Guidance
While you encounter the Customary System of measurement all of the time in your everyday life, there is another
system of measurement that is also widely used. This system is known as the Metric System. In other countries
people use the metric system for the same things that we use the customary system for. We might weigh grapes
using pounds, but in France they use grams to weigh grapes. You may measure the length of one side of your
backyard in feet, but in Beijing they use meters. Even in the United States, the metric system is frequently used
especially in science.
You may find yourself in a situation where you need to convert between the metric system and the customary
system. Take a look at the chart below. It shows the estimated customary equivalent to common metric units.
TABLE 1.1:
Metric Units
1 centimeter
1 meter
1 kilometer
1 milliliter
1 liter
1 gram
1 kilogram
Customary Units
0.39 inches
3.28 feet
0.62 miles
0.2 teaspoons
4.23 cups
0.04 ounces
2.2 pounds
Using this chart can help us to estimate the equivalence between metric units of measurement and customary
units of measurement. Let’s look at a problem.
Estimate the equivalent measures from 14 centimeters to inches.
A centimeter is equal to about 0.39 inches, so we multiply 14 · 0.39 = 5.46 inches
Estimate the equivalent measures from 7.7 pounds to kilograms.
There are 2.2 pounds in 1 kilogram, so we divide the number of pounds by the number of pounds in 1
kilogram. 7.7 ÷ 2.2 = 3.5
The answer is 3.5 kilograms.
If you keep this chart in mind, you will always be able to estimate measures. If you do this enough, you will
be able to figure some of them out without the chart.
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Most runners know that a 5k race is about 3.1 miles. Where as a 10k is 6.2 miles.
Here are a few for you to try on your own. Estimate each equivalent metric measure.
Example A
.16 ounces = ____ grams
Solution: 4 grams
Example B
6 pounds = ____ kilograms
Solution: 3 kilograms
Example C
12 feet = ____ meters
Solution: 3 meters
Here is the original problem once again.
Let’s say that you wanted to make a cake which needed 2 cups of milk. Could you estimate a conversion of two cups
of milk to liters?
To convert cups to liters, let’s think about how many cups equals 1 liter.
4.23 cups is equal to 1 liter.
Our recipe calls for a little less than half the cups needed to equal 1 liter.
Therefore, we can say that 2 cups is approximately equal to .5 liters.
This is our answer.
Vocabulary
Customary System
The system of measurement that includes inches, feet, miles, pounds, tons, cups, quarts, gallons, etc.
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Chapter 1. Conversion Estimation between Systems of Measure
Metric System
The metric system is a system of measurement commonly used outside of the United States. It contains units
such as meters, liters, and grams.
Guided Practice
Here is one for you to try on your own.
How many cups is 16 liters?
Answer
To figure this out, we can use the equivalent measure of cups to liters.
4.23 cups = 1 liter
We can round down to 4 cups = 1 liters to estimate accurately.
Now we want to figure out the number of cups in 16 liters, so we can multiply to figure this out.
4 × 16 = 64
There are about 64 cups in 16 liters.
Video Review
MEDIA
Click image to the left or use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/5401
This is a Khan Academy video on customary and metric units of measurement.
Explore More
Directions: Estimate a customary equivalent for the following metric measurements.
1. 4 kilograms to pounds
2. 7.5 meters to feet
3. 6 liters to cups
4. 13.25 kilometers to miles
5. 6 kilometers to miles
6. 8 liters to cups
7. 20 kilograms to pounds
8. 12 meters to feet
Directions: Estimate a metric equivalent for the following customary measurements, round to the nearest hundredth
where necessary.
9. 4 quarts to liters
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10. 34 ounces to grams
11. 52 pounds to kilograms
12. 9 inches to centimeters
13. 14 feet to meters
14. 16 cups to liters
15. 5 miles to kilometers
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