The scale of a map shows the relationship between a distance on the map and the corresponding distance on the ground. All maps are reduced from actual size, and most printed maps are drawn to a single consistent scale.

 

Scale can be described in several different ways:

 

1.      Graphically as a line somewhere on the map (usually in the margin), marked with distances, such as miles or kilometres.

 

2.      Verbally, as a statement, such as ‘1 inch to 1 mile’ or ‘2 centimetres = 1 kilometre’. Inches tend to be used on older maps and centimetres on newer maps, though some still use inches.

 

3.      As a ratio or representative fraction (RF) such as 1:50,000 or 1:250,000

 

The following are a selection of verbal statements and fractions for common map scales:

 

 

Verbal Scale	Fraction
50 inches to 1 mile	1:1,250
25 inches to 1 mile	1:2,500
10 cm = 1 km	1:10,000
6 inches to 1 mile	1:10,560
2½ inches to 1 mile	1:25,000
2 cm = 1 km	1:50,000
1 inch to 1 mile	1:63,360
1 cm = 1 km	1:100,000
½ inch to 1 mile	1:126,720
2 cm = 5 km	1:250,000
¼ inch to 1 mile	1:253,440
1 cm = 5 km	1:500,000
1 inch to 10 miles	1:633,600
1 cm = 10 km	1:1,000,000

 

 

Maps are often referred to as large-scale or small-scale, the bigger the number after the colon in the RF the smaller the scale of the map. What constitutes a large-scale or small-scale map varies; the Library uses the following definitions:

 

• Large Scale: larger than 1:25,000
• Medium Scale: 1:25,000 – 1:250,000
• Small Scale: smaller than 1:250,000

 

Items at a scale larger than 1:100 are often treated as architectural drawings or engineering plans rather than maps.