Map Scale

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Map scale is a statement that relates distance on a map to distance on the Earth’s surface. It is perhaps the most important information on a map, since the level of detail and map accuracy are both factors of the map scale. Scale is directly related to the map extent, or the area of the Earth’s surface to be mapped. If a relatively small area is to be mapped, such as a neighborhood or subdivision, then the scale can be larger. If a large area is to be mapped, such as an entire continent, the scale must be smaller. Generally, the smaller the scale, the less detailed the map can be. As a rule, anything smaller than 1:250,000 is considered small-scale.

Scale can be reported in several ways, including:

  • representative fraction
  • verbal statement
  • scale bar

Use the Scale Bar tool to automatically create representative fractions and scale bars. Use the Text tool to create a verbal statement.

Representative Fraction

Map scale is often noted as a simple ratio or fraction called a representative fraction. A map in which one inch on the map equals 24,000 inches on the ground could be described as having a scale of 1:24,000 or 1/24,000. The units on both sides of the ratio must be the same.

Verbal Statement

A verbal statement of scale describes the distance on the map to the distance on the ground. A verbal statement describing a scale of 1:1,000,000 is approximately 1 inch to 16 miles. The units on the map and on the ground do not have to be the same in a verbal statement. One-inch and 6-inch maps of the British Ordnance Survey are often referred to by this method (1 inch to 1 mile, 6 inches to 1 mile) (Robinson and Sale, 1969).

Scale Bars

A scale bar is a graphic annotation element that describes map scale. It shows the distance on paper that represents a geographical distance on the map. Maps often include more than one scale bar to indicate various measurement systems, such as kilometers and miles.

Sample Scale Bars

cartography_map_scale_bars

Common Map Scales

You can create maps with an unlimited number of scales, however, there are some commonly used scales. Common Map Scales Table lists these scales and their equivalents (Robinson and Sale, 1969).

Common Map Scales Table

Map Scale

1/40 inch represents

1 inch represents

1 centimeter represents

1 mile is represented by

1 kilometer is represented by

1:2,000

4.200 ft

56.000 yd

20.000 m

31.680 in

50.00 cm

1:5,000

10.425 ft

139.000 yd

50.000 m

12.670 in

20.00 cm

1:10,000

6.952 yd

0.158 mi

0.100 km

6.340 in

10.00 cm

1:15,840

11.000 yd

0.250 mi

0.156 km

4.000 in

6.25 cm

1:20,000

13.904 yd

0.316 mi

0.200 km

3.170 in

5.00 cm

1:24,000

16.676 yd

0.379 mi

0.240 km

2.640 in

4.17 cm

1:25,000

17.380 yd

0.395 mi

0.250 km

2.530 in

4.00 cm

1:31,680

22.000 yd

0.500 mi

0.317 km

2.000 in

3.16 cm

1:50,000

34.716 yd

0.789 mi

0.500 km

1.270 in

2.00 cm

1:62,500

43.384 yd

0.986 mi

0.625 km

1.014 in

1.60 cm

1:63,360

0.025 mi

1.000 mi

0.634 km

1.000 in

1.58 cm

1:75,000

0.030 mi

1.180 mi

0.750 km

0.845 in

1.33 cm

1:80,000

0.032 mi

1.260 mi

0.800 km

0.792 in

1.25 cm

1:100,000

0.040 mi

1.580 mi

1.000 km

0.634 in

1.00 cm

1:125,000

0.050 mi

1.970 mi

1.250 km

0.507 in

8.00 mm

1:250,000

0.099 mi

3.950 mi

2.500 km

0.253 in

4.00 mm

1:500,000

0.197 mi

7.890 mi

5.000 km

0.127 in

2.00 mm

1:1,000,000

0.395 mi

15.780 mi

10.000 km

0.063 in

1.00 mm

The Pixels per Inch for Selected Map Scales Table shows the number of pixels per inch for selected scales and pixel sizes.

Pixels per Inch for Selected Map Scales Table

SCALE

Pixel Size (m)

1"=100’
1:1200

1"=200’
1:2400

1"=500’
1:6000

1"=1000’
1:12000

1"=1500’
1:18000

1"=2000’
1:24000

1"=4167’
1:50000

1"=1 mile
1:63360

1

30.49

60.96

152.40

304.80

457.20

609.60

1270.00

1609.35

2

15.24

30.48

76.20

152.40

228.60

304.80

635.00

804.67

2.5

12.13

24.38

60.96

121.92

182.88

243.84

508.00

643.74

5

6.10

12.19

30.48

60.96

91.44

121.92

254.00

321.87

10

3.05

6.10

15.24

30.48

45.72

60.96

127.00

160.93

15

2.03

4.06

10.16

20.32

30.48

40.64

84.67

107.29

20

1.52

3.05

7.62

15.24

22.86

30.48

63.50

80.47

25

1.22

2.44

6.10

12.19

18.29

24.38

50.80

64.37

30

1.02

2.03

5.08

10.16

15.240

20.32

42.33

53.64

35

.87

1.74

4.35

8.71

13.08

17.42

36.29

45.98

40

.76

1.52

3.81

7.62

11.43

15.24

31.75

40.23

45

.68

1.35

3.39

6.77

10.16

13.55

28.22

35.76

50

.61

1.22

3.05

6.10

9.14

12.19

25.40

32.19

75

.41

.81

2.03

4.06

6.10

8.13

16.93

21.46

100

.30

.61

1.52

3.05

4.57

6.10

12.70

16.09

150

.20

.41

1.02

2.03

3.05

4.06

8.47

10.73

200

.15

.30

.76

1.52

2.29

3.05

6.35

8.05

250

.12

.24

.61

1.22

1.83

2.44

5.08

6.44

300

.10

.30

.51

1.02

1.52

2.03

4.23

5.36

350

.09

.17

.44

.87

1.31

1.74

3.63

4.60

400

.08

.15

.38

.76

1.14

1.52

3.18

4.02

450

.07

.14

.34

.68

1.02

1.35

2.82

3.58

500

.06

.12

.30

.61

.91

1.22

2.54

3.22

600

.05

.10

.25

.51

.76

1.02

2.12

2.69

700

.04

.09

.22

.44

.65

.87

1.81

2.30

800

.04

.08

.19

.38

.57

.76

1.59

2.01

900

.03

.07

.17

.34

.51

.68

1.41

1.79

1000

.03

.06

.15

.30

.46

.61

1.27

1.61

Courtesy of D. Cunningham and D. Way, The Ohio State University

The Number of Acres and Hectares per Pixel Table lists the number of acres and hectares per pixel for various pixel sizes.

Number of Acres and Hectares for Ground Pixel Size

Pixel Size (m)

Acres

Hectares

1

0.0002

0.0001

2

0.0010

0.0004

2.5

0.0015

0.0006

5

0.0062

0.0025

10

0.0247

0.0100

15

0.0556

0.0225

20

0.0988

0.0400

25

0.1544

0.0625

30

0.2224

0.0900

35

0.3027

0.1225

40

0.3954

0.1600

45

0.5004

0.2025

50

0.6178

0.2500

75

1.3900

0.5625

100

2.4710

1.0000

150

5.5598

2.2500

200

9.8842

4.0000

250

15.4440

6.2500

300

22.2394

9.0000

350

30.2703

12.2500

400

39.5367

16.0000

450

50.0386

20.2500

500

61.7761

25.0000

600

88.9576

36.0000

700

121.0812

49.0000

800

158.1468

64.0000

900

200.1546

81.0000

1000

247.1044

100.0000

Courtesy of D. Cunningham and D. Way, The Ohio State University