What scale are OS maps?

Ordnance Survey Explorer maps are 1:25,000 (4cm = 1km). OS Landranger maps are 1:50,000 (2cm = 1km). Harvey maps come in 1:25,000 and 1:40,000 scales. For mountain navigation, 1:25,000 is preferred as it shows field boundaries, walls and detailed terrain features.

How do I measure distance on a map?

Use a piece of string or the edge of a compass baseplate to follow the path, then measure the string against the map scale bar. Map measurers (opisometers) roll along the route and give a direct distance reading. For straight-line distances, use a ruler directly on the map.

Does map distance account for hills?

No, map distance is the horizontal (flat) distance. The actual walking distance over hills is longer due to the slope. For a rough correction, add 10-15% for hilly terrain. A gradient of 30% adds about 5% to the horizontal distance.

CampCalcs

Map Distance Calculator

Convert map measurements to real-world distances using your map scale.

Map Distance

Measured on the map

Map Scale

How We Calculate This

Real distance = Map distance × Scale factor

On a 1:25,000 map, 1cm represents 250m (0.25km). On a 1:50,000 map, 1cm represents 500m (0.5km).

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always verify conditions and use proper safety equipment outdoors.