Map scales and real distances

Convert a map length to a real length using a ratio scale such as 1:25000.

Key formulas

The scale 1:25000 means 1 cm on the map represents 25000 cm in reality, which is 250 m or 0.25 km. Keep units consistent before multiplying.

On a 1:25000 map, two towns are 6.4 cm apart. Real distance = 6.4 × 25000 = 160000 cm = 1600 m = 1.6 km.

A real footpath is 2 km long. In centimetres that is 200000 cm. Map length = 200000 / 25000 = 8 cm.

Problem. A map has scale 1 : 25000. Two towns are 4.8 cm apart on the map. Find the real distance in km.

Solution. Real length = 4.8 × 25000 = 120000 cm = 1200 m = 1.2 km. The towns are 1.2 km apart.

5 cm on the map → 5 × 50000 = 250000 cm = 2.5 km.

Scale 1:10000. Map length 3.5 cm. Real distance in metres is:

Pick one unit and stay with it until the final sentence.

Any unit works if both sides of the ratio use the same unit.