Ordnance Survey – Great Britain's national mapping agency
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The following scales of maps use the National Grid reference system to identify their sheet numbers:1:1250, 1:2500, and 1:10 000.
Although maps at scales smaller than 1:10 000 all carry the National Grid, sheet numbering is based on different principles.
| Graphic series | Data series scale | Map size (km) | Grid intervals | Sheet number |
Direct reference to grid square SW corner (example) | Accuracy |
| Travelmaster® | 1:625 000 | 614 km by 490 km | 10 km | † | TQ 37 | 1 km |
| Travelmaster® | 1:250000 | 190 km by 150 km | 10 km | † | TQ 37 | 1 km |
| Landranger® | 1:50000 | 40 km by 40 km | 1 km | † | TQ 38 77 | 100 m |
| Explorer/Pathfinder® | 1:25000 | 10 Km by 10 Km | 1 Km | TQ 37 | TQ 38 77 | 100 m |
| Landplan® | 1:10000 | 5 Km by 5 Km | 1 Km | TQ 37 NE | TQ 38 77 | 100 m |
| Superplan™ | 1:2500 | 1 Km by 1 Km | 100 m | TQ 38 77 | TQ 388 773 | 10 m |
| 1:1250 | 500 m by 500 m | 100 m | TQ 38 77 SE | TQ 388 773 | 10 m |