# Map Scale

## Producer Field Guide

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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

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 mile1:63360 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