Choose the right map

How to choose the right map

Ordnance Survey publishes maps at several different scales and it's important to choose the right scale for the task. For example, you'll need a very detailed large-scale map when seeking planning permission for a house extension, but a small-scale map if you're planning a journey by car or setting out on a country walk.

To give you an idea of our range, we have some small extracts of our main map scales above. You can click on any of the extracts to see a larger version and get more information about the scale and the map's uses. As all the extracts are centred on the same place (the Big Ben clock tower in Westminster, London), you can see the different amount of detail you get with each scale. Pages containing the larger extracts and more information also have links to the products Ordnance Survey produce at that scale. Just click to be taken to more detailed information about the particular range of maps detailed elsewhere on this web site.

All maps are drawn to scale which means there is a direct relationship between distances measured on the ground and distances measured on the maps. When reading a map, the first thing you should do is establish the scale; it is normally expressed as a ratio, such as 1:50 000. This means that 1 unit of measurement on the map is equal to 50,000 of the same units of measurement on the ground. Maps are also referred to as large- or small-scale. On a large-scale map there is more space to show the surface of the land in more detail. However, mapping at large-scale means that only a smaller area of land can be shown on a sheet of paper of convenient size.