Using the Conversion Factor
Objective: Make unit conversions
Fill in the Missing Numbers
12 inches
1 foot = _____
100 centimeters
1 meter = _____
16
1 pound = _______
ounces
60
1 minute = ______
seconds
60
1 hour = ________
minutes
86,400 seconds
1 day = __________
Unit conversion factor
A unit conversion factor is a fraction whose
numerator and denominator are equivalent
measures. Some common unit conversion factors
are given below. You can also use the reciprocal of
these.
1 ft 1 yd
? in. ? ft
1 mi
? ft
1lb
? oz
1 pt
?c
1 qt 1 gal 1 hr 1 min 1m 1km
? pt ? qt ? min ? s ? cm ? m
Unit conversion factor
A unit conversion factor is a fraction whose
numerator and denominator are equivalent
measures. Some common unit conversion factors
are given below. You can also use the reciprocal of
these.
Choose a unit conversion factor
that…
• Introduces the unit you want in the
answer
• Cancels out the original unit so that
the one you want is all that is left.
“Canceling” out Words
inches feet

feet miles
inches

miles
seconds hours
hours


minutes seconds
minutes
Practice: Choose the appropriate
conversion factor.
Inches to feet
Minutes to hours
Meters to centimeters
inches
1
1 ft
12 in.
minutes
1
60 min
1 hr
meters
1
1m
100 cm
12 in.
1 ft
1 hr
60 min
100 cm
1m
Convert 8 yards to feet…
Make a decision: What conversion factor will you use?
8 yards
1
3 ft
1 yd
or
1 yd
3 ft
Set up the problem: Multiply the measurement by the
conversion factor.
3 ft
8 yd 
1 yd
Hint!
Use the one that will
cancel out the units
Solve the problem: Perform the multiplication
you want to change
3 ft 8 yd 3 ft 24 ft
8 yd 



 24 ft
1 yd
1
1 yd
1
A bucket holds 16 quarts. How many gallons of
water will fill the bucket? Use a unit conversion
factor to convert the units.
What are the two conversion
factors comparing quarts and
gallons?
4 qt
1 gal
Which one will “cancel”
quarts?
16 qt 
16 gal

 4 gal
4
1 gal
4 qt
You Try it!
One bag of apples weighs 64 ounces. How many pounds does it
weigh?
64 oz 
1 lb
64  1 lb

= 4 lb
16 oz
16
Darren drank 2 liters of water. How many milliliters of water did
he drink?
1000 mL
2  1000 mL
2L 

= 2000 mL
1L
1L
Making Rate Conversions
Use a unit conversion to convert the
units within each rate
Convert 80 miles per hour to feet per hour.
80 mi 5,280 ft
80  5280 ft
422,400 ft



1 hr
1 mi
1 hr
1 hr
Convert 63,360 feet per hour to miles per hour.
63,360 ft
1 mi
63,360 ft  1 mi


1 hr
5280 ft
1 hr  5280 ft
12 mi

1 hr
You Try it!
Convert 32 feet per second to inches per second.
32 ft
12 in
32 ft  12 in
384 ft


=
1s
1 ft
1 s  1 ft
1s
A craft store charges $1.75 per foot for lace. How much per yard
is this?
$1.75
3 ft
$1.75  3 ft
$5.25


=
1 ft
1 yd
1 ft  1 yd
1 yd
Word Problems
The average American eats 23 pounds
of pizza per year. Find the number of
ounces the average American eats per
year.
23 lb 16 oz 23  16 368 oz



1 yr 1 lb
1
1 yr
The average American eats 368 ounces
of pizza per year.
General Math click here
Pre-Algebra click here
General Math Homework
Do Practice worksheet for
tomorrow.
Word Problems…
A car traveled 60 miles on a road in 2 hours.
How many feet per second was the car
traveling? Hint: Set up the words first.
mi
ft

hr
mi
hr

s
How many seconds
in an hour?
60 s 60 min 3600 s


1 min 1hr
1 hr
60  5, 280
60 mi 5,280 ft
1 hr




2  3600
2 hr
1 mi
3600 s
The car traveled 44 feet per second.

44 ft
1s
Homework 
Complete Practice Worksheet B