SCALE

The scale of a map refers to the ratio of a distance (or area) on the map to the actual distance on the ground. For example, the scale 1:250,000 means that a distance of 1 unit on the map (eg. 1mm) represents a distance of 250,000 units (250,000mm or 250m) along the ground. Scale on a topographic map can be displayed in one of two ways:

• As a representative fraction (for example 1:100,000)
• As a scale bar. Often both are given at the bottom of a topographic map sheet (see below)

Figure 1: Both forms of scale are depicted on this 1:25,000 topo map sheet (upper is the representative fraction and below it is the scale bar).

Note that the size of the scale of map refers to the relative sizes of features represented on a map. For example a small scale map shows features in a relatively small size (eg. 1:1,000,000), whereas large scale maps show features in a relatively large size (eg. 1:500). The scale of a map will determine the amount of detail which can be shown on it, large scale maps (eg. 1:10,000) being more detailed and a closer approximation to the earth's surface than small scale maps (eg. 1:250,000).