Scale describes the ratio in size between something in the real world and its representation on a map. In other words, if a map has a scale of 1:50 000 then a distance of 1 cm on the map represents 50 000cm (500 m) in the real world.
The main scales used by Ordnance Survey (OS) for surveying are 1:1250, 1:2500 and 1:10 000. These are referred to as large scale maps, which is when features in the real world are portrayed larger on the map.
OS also produce a number of mapping products at other scales, such as 1:25 000 scale and 1:50 000 scale. These are referred to as small scale. On these small scale maps, due to scale restrictions, some features are simplified or generalised. For example, at these scales OS do not show the shapes of individual houses as small maps would have too much detail to be able to read.
- 1:1250 scale is used for surveying cities and towns (urban areas) and is the most accurate OS use
- 1:2500 scale is used for smaller towns and villages (rural areas)
- 1:10 000 scale is used for remote areas, mountain and moorland. Generalisation of features may occur at this scale