Map Scale Calculator
Convert between map measurement and real-world distance for any scale. Works for all Ordnance Survey scales (1:25,000, 1:50,000) and any custom map.
Reading OS Maps
Common OS Map Scales
1:25,000 (Orange OS Explorer): most popular for walking. 4cm on map = 1km reality. Grid squares are 1km. Best for route-finding detail. 1:50,000 (Pink OS Landranger): 2cm = 1km. Covers larger areas. Used for planning and cycling. 1:10,000: detailed street-level mapping.
Grid References
OS maps use a grid reference system. A 6-figure grid reference locates a point within 100m. An 8-figure reference gives 10m precision. To estimate distance between two points: count the number of grid squares in each direction and use Pythagoras if diagonal.
Using a Scale Rule
Most OS maps include a printed scale bar. Place a strip of paper along your route, mark the points, then measure against the scale bar for accurate distance. GPS apps use satellite data for much higher accuracy, but paper map skills remain essential for remote navigation.
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