Map Scales

Scale on a map is defined as the ratio of actual distance to distance on the map. 

Map scale = \( \frac {actual \: distance}{distance \: on \: map} \)

Map scales are normally written in the ratio form 1 : 7 e.g. 1 : 50,000 means 1 cm represents 50,000 cm. 

Example 1.3.1:

Rewrite the scales in ratio form 
a. 1 cm represents 10 m 
b. 1 cm represents 20 cm 
c. 1 cm represents 20 km   

Solution: 

a. 1 cm represents 10 m 

both have different units:

change 10 m to cm. 

1 m =  100 cm 

∴ 10 m = 10 × 100 cm = 1000 cm 

∴ 1 cm : 1000 cm

Scale = 1 : 1000

b. 1 cm represents 20 cm 

both are in the same units 

scale = 1 : 20 

c. 1 cm represents 20 km 

convert 20 km to cm