Turn a distance measured on a map into the real distance on the ground, or work out how long a route will be on paper. Use a ratio scale such as 1:24,000 or a verbal scale such as 1 inch = 1 mile, in metric or US units, or find the scale from two distances.
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What do you want to find?
Scale format
e.g. 24000, 1:50,000 or 1/100000
Distances
Enter your values to see the result.
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How to use the Map Scale Calculator
Choose a direction: map to real, real to map, or find the scale.
Enter the scale as a ratio (1:24,000) or as a verbal scale (1 in = 1 mi).
Type the distance you measured on the map or the real distance, and pick the units.
Press Calculate to see the answer in several units.
Use the table to read off other distances at the same scale, or download it as CSV.
Map scale formulas
Real distance = map distance × N (then convert units)
Map distance = real distance ÷ N (with the real distance in the map unit)
Scale N = real distance ÷ map distance (both in the same unit)
A ratio scale (also called a representative fraction) has no units: 1:24,000 works in inches, centimeters or any other unit, as long as you use the same unit on both sides. A verbal scale like “1 inch = 1 mile” mixes units, so convert it to a ratio first: 1 mile = 63,360 inches, so it is 1:63,360.
Common map scales
Scale
1 cm on the map
1 inch on the map
Typical use
1 : 10,000
100 m
about 833 ft
City plans, orienteering
1 : 24,000
240 m
2,000 ft
US 7.5-minute topographic quadrangles
1 : 25,000
250 m
about 2,083 ft
Hiking maps in many countries
1 : 50,000
500 m
about 0.79 mi
Regional topographic maps
1 : 63,360
about 634 m
1 mile
“Inch to the mile” maps
1 : 100,000
1 km
about 1.58 mi
Regional overview maps
1 : 250,000
2.5 km
about 3.95 mi
Aviation and planning maps
1 : 1,000,000
10 km
about 15.8 mi
Country and state maps
Tips for measuring map distances
Use a ruler for straight lines and a piece of string laid along the route for winding roads and trails.
Check the scale bar on a printed map: a photocopy or a screen zoom changes the size of the map but the scale bar shrinks or grows with it, while the printed ratio no longer applies.
Map distance is horizontal distance. On steep terrain the walking distance is longer, and the time taken depends on the climb as well.
Round at the end, not in the middle: a small rounding error in N is multiplied by every centimeter you measure.
Frequently asked questions
How do you calculate real distance from a map scale?
Multiply the map distance by the scale number N and convert units. On a 1:24,000 map, 3.5 inches is 3.5 × 24,000 = 84,000 inches on the ground, which is 7,000 feet or about 1.33 miles.
How do you convert real distance to map distance?
Convert the real distance to the map unit, then divide by N. On a 1:50,000 map, 2 km = 200,000 cm, and 200,000 ÷ 50,000 = 4 cm on the map.
What does a map scale of 1:24,000 mean?
One unit on the map equals 24,000 of the same unit on the ground: 1 inch = 24,000 inches = 2,000 feet, and 1 cm = 240 m. It is the standard scale of US Geological Survey 7.5-minute topographic maps.
How do I change a verbal scale into a ratio?
Put both sides in the same unit and divide. For 1 inch = 1 mile, 1 mile = 63,360 inches, so the ratio is 1:63,360. For 1 cm = 5 km, 5 km = 500,000 cm, so the ratio is 1:500,000.
How do I find the scale of a map?
Measure the map distance between two points whose real distance you know, convert both to the same unit and divide real by map. If 8 cm on the map is 2 km on the ground, 200,000 ÷ 8 = 25,000, so the scale is 1:25,000.
What is the difference between a large-scale and a small-scale map?
A large-scale map has a small N (like 1:10,000) and shows a small area in great detail. A small-scale map has a large N (like 1:1,000,000) and covers a large area with less detail.
Why is my measured route longer than the calculated distance?
A ruler measures a straight line on flat paper. Roads and trails curve, and hills add distance, so real travel distance is usually longer. Measure curvy routes in short straight pieces and add them up.
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