Length Conversions
Many people are familiar with the U.S. Customary units of measure, either because they are using
them now or have used them in the past. However, the metric system, while commonly used in
many parts of the world, is not always as familiar to people in the United States.
The metric system began as a result of the French National Assembly asking the French Academy of
Sciences to try to standardize the system of weights and measures that had become so confused in
France. In 1791, work on the new system was begun, and by 1795, all metric units had been set
and identified in France. By 1799, the new units were declared the legal standards for every
measurement used in France. In 1875, an international conference met in Paris to set up an
International Bureau of Weights and Measures. Meetings are held to reconsider the way the units
have been determined, and the system has been refined over the years. Today, the metric system,
based on units of 10, has been officially adopted by most of the countries in the world.
Below are two tables. The first shows the equivalency of 1 inch, 1 foot, 1 yard, and 1 mile to
common metric measures. The second shows the equivalency of 1 millimeter, 1 centimeter, 1 meter,
and 1 kilometer to common U.S. Customary measurements. For ease in use, we have rounded the
measurements to two decimal places where possible.
Millimeter
Centimeter
Meter
Kilometer
1 Inch
25.40
2.54
0.03
0.00003
1 Foot
304.80
30.48
0.30
0.0003
1 Yard
914.40
91.44
0.91
0.0009
1 Mile
1609344.00
160934.40
1609.34
1.61
Inch
Foot
Yard
Mile
1 Millimeter
0.04
0.003
0.001
---
1 Centimeter
0.39
0.03
0.01
0.000006
1 Meter
39.37
3.28
1.09
0.0006
1 Kilometer
39370.08
3280.84
1093.61
0.62
How do you convert between the two systems when the need arises? Use the standard methods of
conversion shown in the tables above to solve the following practice problems.
©2016 Bonnie Rose Hudson WriteBonnieRose.com
Activity One:
If we know that 1 inch (in) = 25.4 millimeters (mm) or 2.54 centimeters (cm), find the answers to
the following problems.
3 in. = __________ mm
3 in. = __________ cm
9 in. = __________ mm
7 in. = __________ cm
18 in. = __________ mm
20 in. = __________ cm
25 in. = __________ mm
23 in. = __________ cm
34 in. = __________ mm
36 in. = __________ cm
Activity Two:
Now that you have your answers for the above problems, convert them into metric measurements.
For example, we see that 3 in. equals 76.2 mm or 7.62 cm. There are 10 millimeters in a centimeter.
To convert from millimeters to centimeters, you divide the number of millimeters by 10. To convert
from centimeters to millimeters, you multiply the number of centimeters by 10. Using your answers
in the exercise above, convert the millimeter answers to centimeters, and the centimeter answers to
millimeters. The first one is done for you.
3 in. = 76.2 mm or 7.62 cm
3 in. = 7.62 cm or 76.2 mm
9 in. = _______ mm or _______cm
7 in. = _______ cm or _______mm
18 in. = _______ mm or _______cm
20 in. = _______ cm or _______mm
25 in. = _______ mm or _______cm
23 in. = _______ cm or _______mm
34 in. = _______ mm or _______cm
36 in. = _______ cm or _______mm
©2016 Bonnie Rose Hudson WriteBonnieRose.com
Activity Three:
If we know that 1 cm equals .39 in., convert the following:
16 cm = __________ in.
77 cm = __________ in.
249 cm = __________ in.
94 cm = __________ in.
67 cm = __________ in.
152 cm = __________ in.
83 cm = __________ in.
194 cm = __________ in.
71 cm = __________ in.
239 cm = __________ in.
Activity Four:
Using the fact that 1 foot (ft.) equals .30 meters (m) or 30.48 cm, find the answers to the following
problems:
1.
If you were building a room onto your house and you needed to make it 18 feet by 16 feet,
what would those measurements be in meters? In centimeters?
2.
If you bought a piece of property the measurements of which were 137 feet by 94 feet, what
would those measurements be in meters? In centimeters?
3.
If you were having a driveway paved that measured 12 feet by 20 feet and you had to give
those measurements in meters, what would the measurements be? What would they be in
centimeters?
4.
Knowing there are 3 feet in a yard, how many meters of material would you need to buy if
you were making something that required 6 yards of material?
5.
For a race, you are making lines on the ground 15 feet apart so you can see who is in the
lead at different points in the race. How many meters apart are the lines?
©2016 Bonnie Rose Hudson WriteBonnieRose.com
Activity Five:
Now, using the fact that 1 m = 3.28 ft., compute the following:
16 m = __________ ft.
27 m = __________ ft.
23 m = __________ ft.
12 m = __________ ft.
35 m = __________ ft.
18 m = __________ ft.
52 m = __________ ft.
43 m = __________ ft.
30 m = __________ ft.
9 m = __________ ft.
Activity Six:
Using the fact that 1 mile (mi.) equals 1.61 kilometers (km), do the following problems:
1.
You are driving and see a sign that tells you your destination is 14 miles away. How many
kilometers does that equal?
2.
When figuring the distance to travel on your vacation, you find you will have to travel 175
miles. How many kilometers do you have to travel?
3.
Your friend is coming to visit and tells you they have to make extra stops on the way, so they
will be traveling a total of 83 miles. How many kilometers will they travel?
4.
You have to total the distance traveled for reimbursement. You traveled 30 miles on Monday,
21 miles on Tuesday, 16 miles on Wednesday, and 9 miles on Thursday. How many total kilometers
did you travel?
5.
You need to determine the total distance to your grandmother’s house from your new home.
Your grandmother lived 3 miles from your old home and you have moved 2 miles further away. How
many kilometers do you now live from your grandmother’s house?
©2016 Bonnie Rose Hudson WriteBonnieRose.com
Activity Seven:
Knowing that 1 km = .62 mi., do the following problems:
73 km = __________ mi.
94 km = __________ mi.
19 km = __________ mi.
42 km = __________ mi.
28 km = __________ mi.
61 km = __________ mi.
97 km = __________ mi.
32 km = __________ mi.
59 km = __________ mi.
17 km = __________ mi.
©2016 Bonnie Rose Hudson WriteBonnieRose.com
Answer Key:
Activity One:
3 in. = 76.2 mm
3 in. = 7.62 cm
9 in. = 228.6 mm
7 in. = 17.78 cm
18 in. = 457.2 mm
20 in. = 50.8 cm
25 in. = 635 mm
23 in. = 58.42 cm
34 in. = 863.6 mm
36 in. = 91.44 cm
Activity Two:
3 in. = 76.2 mm or 7.62 cm
3 in. = 7.62 cm or 76.2 mm
9 in. = 228.6 mm or 22.86 cm
7 in. = 17.78 cm or 177.8 mm
18 in. = 457.2 mm or 45.72 cm
20 in. = 50.8 cm or 508 mm
25 in. = 635 mm or 63.5 cm
23 in. = 58.42 cm or 584.2 mm
34 in. = 863.6 mm or 86.36 cm
36 in. = 91.44 cm or 914.4 mm
Activity Three:
16 cm = 6.24 in.
77 cm = 30.03 in.
249 cm = 97.11 in.
94 cm = 36.66 in.
67 cm = 26.13 in.
152 cm = 59.28 in.
83 cm = 32.37 in.
194 cm = 75.66 in.
71 cm = 27.69 in.
239 cm = 93.21 in.
Activity Four:
1.
5.4 m by 4.8 m or 548.64 cm by 487.68 cm
2.
41.1 m by 28.2 m or 4175.76 cm by 2865.12 cm
3.
3.6 m by 6 m or 365.76 by 609.60 cm
4.
5.4 m
5.
4.5 m
©2016 Bonnie Rose Hudson WriteBonnieRose.com
Activity Five:
16 m = 52.48 ft.
27 m = 88.56 ft.
23 m = 75.44 ft.
12 m = 39.36 ft.
35 m = 114.8 ft.
18 m = 59.04 ft.
52 m = 170.56 ft.
43 m = 141.04 ft.
30 m = 98.4 ft.
9 m = 29.52 ft.
Activity Six:
1.
22.54 km
2.
281.75 km
3.
133.63 km
4.
122.36 km
5.
8.05 km
Activity Seven:
73 km = 45.26 mi.
94 km = 58.28 mi.
19 km = 11.78 mi.
42 km = 26.04 mi.
28 km = 17.36 mi.
61 km = 37.82 mi.
97 km = 60.14 mi.
32 km = 19.84 mi.
59 km = 36.58 mi.
17 km = 10.54 mi.
©2016 Bonnie Rose Hudson WriteBonnieRose.com