Map Scale Distance Calculator
Convert a measured distance on a paper or digital map to real-world distance using standard Ordnance Survey and custom map scales.
Results
What is it?
A map scale ratio tells you how many real-world units correspond to one unit on the map. A 1:50,000 map means 1 cm on paper equals 50,000 cm (500 m or 0.5 km) in reality. Ordnance Survey Explorer maps (1:25,000) are ideal for walkers � 4 cm = 1 km. Landranger maps (1:50,000) show 2 cm = 1 km.
How to use
Measure the distance between two points on your map with a ruler. Enter that measurement in centimetres, select your map scale (or enter a custom denominator), and the calculator converts it to real-world kilometres and miles.
Example scenario
On a 1:50,000 OS Landranger map you measure 7.5 cm between a car park and a summit. Real distance = 7.5 x 50,000 cm = 375,000 cm = 3.75 km (2.33 miles). Allow for terrain � actual walking distance on undulating paths will be greater.
Pro tip
For hiking, always add 10-20% to straight-line map distance to account for path meanders and terrain. Use map wheels (opisometers) or digital tools to measure curved paths. Naismith's Rule adds 1 hour per 600 m of ascent to walking time � factor elevation change from contour lines.