1) Map scale indicates the ratio between the distance on a map and the actual distance on Earth. It is expressed either graphically with a bar scale or fractionally as a ratio like 1:24,000. 2) Graphic scales allow direct measurement of distances on a map. Fractional scales require calculating the actual distance by multiplying the measured distance by the denominator of the scale ratio. 3) Examples show how to use fractional scales to determine distances in other units like feet, miles, or meters based on the map's scale ratio.

1. MapMap
ScaleScale
Lab ThreeLab Three

2. Map Scale
• The scale of a map
indicates how much
the Earth has been
reduced for
reproduction on that
map.

3. • In practical terms, scale is the relationship
between the distance shown on a map
and the actual distance that it represents
on the Earth.
Map Scale

4. Ways to Indicate Scale
1. Graphic scales
– See figure 1 in lab
manual
2. Fractional scales
– Example 1:24,000
Graphic Scale
There are two common ways to indicate the scale of a map:

5. Graphic Scales
• The graphic scale of a
map is a bar graph
graduates by
distance.
– Figure one in the lab
manual shows the
graphic map scale
from a U.S. Geological
Survey topographic
map.

6. • To use a graphic scale, simply measure a
distance on the map (or mark off the
distance on the edge of a piece of paper),
then compare the measured distance to
the bar graph to determine the actual
distance represented.
Graphic Scales

7. On some graphic scales, “zero” is not at the far left, this
is to make it easier to read fractions.
Graphic Scales

8. • Graphic scales are useful since they
remain accurate even if the map is
enlarged or reduced.
Graphic Scales

9. Fractional Scale
• The fractional scale or
the representative
scale expresses the
scale of a map as a
fraction or ratio.
– 1/24,000 or 1:24,000

10. Fractional Scale: 1/24,000 or
1:24,000
• This scale, which is read “one to twenty-
four thousand”, says that one unit of
measurement on the map represents
24,000 units of measurement on the
Earth.

11. • At this scale, one centimeter on the map
represents an actual distance of 24,000
centimeters on the Earth, and one inch on
the map equals 24,000 inches on the
map.
– Units of measurement must be the same in
both the numerator and the denominator.
Fractional Scale: 1/24,000 or
1:24,000

12. Computing Distances with
Fractional Scales
1. Use a ruler to measure the
distance on the map in inches
(or centimeters). This is the
measured distance.
2. Multiply the measured distance
by the map’s fractional scale
denominator. This will give you
the actual distance in inches (or
centimeters).
3. To convert your actual distance
in inches (or centimeters) to
other units, use the following
formulas:
To determine distances represented on a map by
using the fractional scale:

13. Conversions
• To determine the distance in feet, actual
distance in inches / 12
• To determine the distance in miles, actual
distance in inches / 63,360
• To determine the distance in meters,
actual distance in centimeters / 100
• To determine the distance in kilometers,
actual distance in centimeters / 100,000

14. English Measurements
• 1 mile = 5280 ft
• 1 mile = 63360 inches
• 1 foot = 12 inches

15. Metric Measurements
• 1 Kilometer (Km) = 1,000 meters (m)
• 1 Kilometer (Km) = 100,000 cm
• 1 Kilometer (Km) = 1,000,000 mm
• 1 meter = 100 centimeters (cm)
• 1 centimeter = 10 millimeters (mm)

16. Examples
• If a map has a scale of 1/24,000, a
measured distance of 8.25 inches on the
map represents an actual distance of
198,000 inches
– 8.25 X 24,000 = 198,000 inches
– 198,000 inches / 12 = 16,500 feet
– 198,000 inches / 63,360 = 3.1 miles

17. Examples
• If a map has a scale of 1/50,000, a
measured distance of 22 centimeters on
the map represents an actual distance of
1,100,000 cm
– 22 cm X 50,000 = 1,100,000 cm
• To calculate the actual distance in meters
and kilometers:
– 1,100,000 cm / 100 = 11,000 meters
– 1,100,000 cm / 100,000 = 11 kilometers

18. Large Versus Small Scale Maps
• Large scale maps refer to maps with a relatively large
representative fraction such as 1/10,000.
– Large scale maps show a small area of the Earth in great detail.
• Small scale maps refer to maps with a relatively small
representative fraction like 1/1,000,000.
– Small scale maps show large areas in less detail.
Small Scale Medium Scale Large Scale