Map Scale Calculator
Measure a distance on a map and get the real distance, or enter a real distance and get the length to draw — at any scale such as 1:50,000. You can also work backwards: give a map distance and the distance it represents and get the representative fraction and the verbal scale (for example, 1 cm = 500 m). Every step is shown. Runs entirely in your browser — free, no sign-up.
Type 1:50000, 1:24,000 or just 50000. Two numbers a:b mean 1 unit on the map is b ÷ a on the ground.
Results
1.7 km
Real distance
1:50,000
Representative fraction
1 cm on the map = 500 m on the ground
Verbal scale
1 cm² on the map = 25 ha on the ground
A bigger N is a smaller-scale map: it shows more ground in less detail.
The working
3.4 cm = 0.034 m on the map; × 50,000 = 1,700 m = 1.7 km on the ground.
What one map length means on the ground
| On the map | On the ground (metric) | On the ground (imperial) |
|---|---|---|
| 1 mm | 50 m | 164 ft |
| 1 cm | 500 m | 1,640 ft |
| 10 cm | 5 km | 3.107 mi |
| 1 in | 1.27 km | 4,167 ft |
What one ground distance looks like on the map
| On the ground | On the map (cm) | On the map (in) |
|---|---|---|
| 100 m | 0.2 | 0.07874 |
| 1 km | 2 | 0.7874 |
| 5 km | 10 | 3.937 |
| 1 mi | 3.219 | 1.267 |
How to Use the Map Scale Calculator
- 1. Choose the question. Real distance from a map distance answers “how far is it?”. Map distance from a real distance answers “how long should I draw it?”. The scale from two distances finds the scale when you know both.
- 2. Enter the scale as written on the map. 1:50000, 1:24,000 and 1/25000 all work, and so does the bare number. Pick the unit of each distance and the unit you want the answer in.
- 3. Read the answer, the verbal scale and the working. The result card gives the converted distance; the working line shows the multiplication or division in metres.
- 4. Use the tables. They show what 1 mm, 1 cm, 10 cm and 1 inch mean on the ground at this scale, and how long 100 m, 1 km, 5 km and 1 mile are on the map.
What a Map Scale Means
A map scale compares a distance on the map with the matching distance on the ground. Written as a representative fraction, 1:50,000, it says that one unit on the map stands for 50,000 of the same unit on the ground: 1 cm is 50,000 cm, which is 500 m. Because the fraction has no units, it works for centimetres, inches or anything else. The same relationship written in words is a verbal scale — “1 cm to 500 m”, “1 inch to 1 mile” — and a scale bar draws it as a ruler, which is the only form that stays correct if the map is photocopied or resized.
| Representative fraction | Verbal scale | Typical use |
|---|---|---|
| 1:10,000 | 1 cm = 100 m | Town plans, orienteering maps |
| 1:24,000 | 1 inch = 2,000 ft | US topographic quadrangles |
| 1:25,000 | 4 cm = 1 km | Walking maps (UK Explorer) |
| 1:50,000 | 2 cm = 1 km | Topographic and hiking maps (UK Landranger) |
| 1:63,360 | 1 inch = 1 mile | Old UK one-inch maps |
| 1:250,000 | 1 cm = 2.5 km | Regional maps |
A larger number after the colon is a smaller-scale map: it covers more ground with less detail.
The Three Calculations
- Ground distance = map distance × N. A road measures 3.4 cm on a 1:50,000 map: 3.4 cm × 50,000 = 170,000 cm = 1.7 km.
- Map distance = ground distance ÷ N. A 5 km walk on a 1:25,000 map is 5000 m ÷ 25,000 = 0.2 m, or 20 cm.
- Scale N = ground distance ÷ map distance, both in the same unit. If 4 cm on a map stands for 2 km, N = 200,000 cm ÷ 4 cm = 50,000, so the scale is 1:50,000.
Worked example: 1 inch to 1 mile
1 mile = 5,280 ft × 12 = 63,360 inches.
N = 63,360 ÷ 1 = 63,360, so the scale is 1:63,360. In metric terms 1 cm on the map is 633.6 m on the ground.
Scales apply to length, so areas scale with N². At 1:50,000, 1 cm² of map shows 500 m × 500 m = 250,000 m² or 25 hectares. This is also why enlarging a map by photocopier breaks a printed 1:50,000 label: the bar scale stretches with the page but the written fraction does not. Remember too that a map measures distances over a flat projection: for long distances use the great-circle Latitude Longitude Distance Calculator, and measure along a path with a piece of string rather than a straight ruler when the route winds.
Frequently Asked Questions
- How do you calculate real distance from a map scale?
- Measure the distance on the map, then multiply it by the number after the colon. At 1:50,000, 3.4 cm becomes 3.4 × 50,000 = 170,000 cm, which is 1.7 km. Convert to kilometres or miles at the end.
- How do you convert a map scale of 1:50,000 to a verbal scale?
- Pick a convenient map length and multiply: 1 cm × 50,000 = 50,000 cm = 500 m, so 1 cm represents 500 m (or 2 cm to 1 km). In imperial units, 1 inch represents 50,000 inches, a little under 0.79 miles.
- What is a larger-scale map?
- A map with a smaller N. A 1:10,000 map is larger-scale than a 1:100,000 map: features are drawn bigger and in more detail, but the map covers less ground.
- How do I find the scale of a map from two known points?
- Measure the distance between the points on the map, look up or calculate their real distance, convert both to the same unit and divide ground by map. If 4 cm on the map is 2 km, the scale is 200,000 cm ÷ 4 cm = 1:50,000.
- Does the map scale change when I print or zoom a map?
- The printed fraction stays the same but the true scale changes with the enlargement. A 1:50,000 map shrunk to 50 % is really 1:100,000. Use the scale bar printed on the map, which resizes with it, or measure a known distance to check.
- What does 1:1 or 2:1 mean?
- Ratios at or above 1:1 are used for enlarged drawings of small objects, such as a 2:1 diagram of an insect drawn twice life size. The calculator reads 2:1 as N = 0.5: one unit on the drawing is half a unit on the real object.