Map Scale Calculator
Convert map distances to real distances for any map scale.
About this tool
Enter the scale (or pick a common one), then a distance measured on the map to get the real distance, or a real distance to get its length on the map. You can also work out a map's scale from a known distance.
Reading map scales
A ratio scale such as 1:25,000 means one unit on the map equals 25,000 of the same unit on the ground. So 1 cm on the map is 25,000 cm, or 250 m, and 4 cm is exactly 1 km. That's why the 1 km grid squares on UK Ordnance Survey Explorer maps measure 4 cm. On a 1:50,000 Landranger map, 2 cm is 1 km; on a US Geological Survey 1:24,000 topographic quad, 1 inch is 2,000 feet; and 1:63,360 is the old 'inch to the mile'. To convert, multiply the map distance by the scale and change units; to go the other way, divide. To find an unknown scale, divide the real distance by the map distance in the same units: 8 cm covering 2 km is 1:25,000. The tool also shows the verbal scale (1 cm = 250 m; 1 inch = 0.39 miles) for quick mental maths. Honest limits: straight-line map distances understate walking distance on winding paths and ignore height gain, so measure along the route and allow extra time for hills. Printed or zoomed maps may not be at their stated scale, so check against the scale bar. The distance between coordinates calculator and the pace calculator are related.
Frequently asked questions
What does 1:25,000 mean on a map?
1 cm on the map is 25,000 cm (250 m) on the ground, so 4 cm is 1 km.
How do I convert map distance to real distance?
Multiply the map distance by the scale denominator, then convert units: 3 cm ร 50,000 = 150,000 cm = 1.5 km.
What scale is 1 inch to a mile?
1:63,360, since a mile has 63,360 inches.
How do I find the scale of a map?
Measure a known distance on the map, then divide the real distance by the map distance in the same units.
Is my data sent anywhere?
No. Everything is calculated in your browser, and nothing is stored or sent.