The scale of a map shows the ratio between the distances on the map and the corresponding distances in reality. For example, a map of scale 1:50,000 shows a distance of 50,000 cm (or 500 m) as 1cm on a map. A 1:25 scale model of a building with a height of 30 m has a model height of 1.20 m.

When a drawing or model or photograph of an object is larger or smaller than the original, the scale represents how much the object has been "grown" or "shrunk".

Scale bars for microscopic or unusual objects are necessary. They help readers to understand the diagram.

• Proportionality
• Scale (map)