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