Map Scale Distance Converter
Measure a distance on your map, enter the map scale, and instantly see the real-world distance in kilometres, miles, metres, and nautical miles. Add multiple legs for a full route total with estimated walking time. Nothing uploaded.
Map Scale
Mode
OS map guide
- 1:10,000 - Street detail, surveying
- 1:25,000 - Explorer: footpaths, field boundaries
- 1:50,000 - Landranger: long routes, cycling
- 1:100,000 - Road planning, overview
- 1:250,000 - Regional / road atlas
Route Legs
| # | Map dist (mm) | Ascent (m) ? | Real distance |
|---|
Route Totals
Real World - Map
Learn more: map scales and distance estimation
Understanding map scales and real-world distance
A map scale like 1:25,000 means 1 unit on the map equals 25,000 units in real life. So 1 cm on a 1:25,000 map equals 250 metres. On a 1:25,000 map, 40 mm on the map equals 1 km in real life. Common OS maps: Explorer maps are 1:25,000 (more detail), Landranger maps are 1:50,000 (bigger area). The calculator lets you pick any standard scale or enter a custom denominator.
Bidirectional conversion and multi-leg routes
Works in both directions - enter a map measurement and get real-world distance, or enter a real-world distance and get the equivalent map measurement. For multi-stage hikes, add multiple route legs each with a different distance and optional ascent value. The calculator totals everything instantly in metres, km, miles, and nautical miles.
Naismith's rule for hiking time estimates
Naismith's rule estimates hiking time as 1 hour per 5 km of horizontal distance, plus 1 extra minute for every 10 m of ascent. For example, a 10 km route with 500 m of climbing takes about 2 hours + 50 minutes = 2 hours 50 minutes. The rule does not account for descents or rough terrain, so add a buffer for real-world conditions. The calculator applies Naismith's rule automatically if you enter height gain per leg.
FAQ
On a 1:25,000 map, how many mm equals 1 km?
On a 1:25,000 map, 40 mm on the map equals 1 km in real life. The scale means 1 mm on map = 25,000 mm = 25 m. So 1 km / 25 m = 40 mm.
What is the difference between a 1:25,000 and a 1:50,000 map?
A 1:25,000 map shows twice as much detail as a 1:50,000. On a 1:25,000, 1 cm = 250 m. On a 1:50,000, 1 cm = 500 m. OS Explorer maps are 1:25,000. OS Landranger maps are 1:50,000. Use 1:25,000 for walking and navigation, 1:50,000 for longer routes and cycling.
What is Naismith's rule for estimating walking time?
Naismith's rule estimates hiking time as 1 hour per 5 km of horizontal distance, plus 1 extra minute for every 10 m of ascent. For example, a 10 km route with 500 m of climbing takes about 2 hours + 50 minutes = 2 hours 50 minutes. The calculator adds ascent automatically if you enter height gain per leg.