Maps & scale

A city is many kilometres across, a sheet of paper only a few centimetres. Yet a city map shows you every street. The trick: maps show the Earth shrunk down, with all distances reduced by the same ratio. If you can read a map, you can plan hikes, estimate routes and find your way around unfamiliar cities.

The scale: the map's shrink factor

The scale tells you how much a map shrinks the world. It is usually printed at the edge, for example 1:25,000. That means: 1 cm on the map is 25,000 cm in reality. To work out a real distance, measure the route on the map in cm and multiply by the scale number. Example: 2 cm on a 1:25,000 map is 2 x 25,000 = 50,000 cm, which is 500 m. The smaller the scale number, the less was shrunk and the more detail you see: a city map uses 1:10,000, a hiking map 1:25,000, a world map 1:50,000,000. Even a globe 30 cm across shows the Earth only at roughly 1:42,000,000.

Compass directions and the legend

So that every map reads the same way, almost all of them follow one rule: north is up, south is down, west is left and east is right. The legend is the map's dictionary: it explains what the colours and symbols mean, such as blue for water, green for forest and a black rectangle for a building. Always check the scale and the legend first before using a map.

Contour lines: mountains on flat paper

How does a flat map show a mountain? With contour lines. Each line connects points at the same height, for example every point at 400 m. On one map, neighbouring lines are always the same height apart, usually 10 m or 20 m on hiking maps. So if the lines are close together, the slope is steep, because the ground climbs many metres over a short distance. If they are far apart, the terrain is flat. That way you can tell at home whether a hike will be relaxed or sweaty.