Map scale shows the relationship between distances on a map and corresponding distances on the ground. There are several ways to determine a map's scale:
Understanding Map Scales
Maps use different methods to represent scale:
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Verbal Scale: This directly states the relationship, for example, "1 inch = 1 mile" or "1 cm = 1 km". This is the easiest to understand. To use it, simply measure the distance on the map using a ruler and then apply the scale. For example, if the distance on the map is 3 inches and the scale is "1 inch = 1 mile", the actual distance is 3 miles.
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Representative Fraction (RF) Scale: This is expressed as a ratio, such as 1:100,000 or 1/100,000. This means one unit on the map represents 100,000 of the same units on the ground (e.g., 1 cm on the map equals 100,000 cm or 1 km on the ground).
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Graphic Scale (Bar Scale): This is a visual representation of the scale using a line divided into segments that correspond to ground distances. This is useful because it remains accurate even if the map is enlarged or reduced. You simply measure the distance on your map and compare it to the scale bar.
Measuring Distances on a Map
To measure the distance between two points on a map, you will need a ruler.
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Using a Verbal or RF Scale: Measure the distance between the two points on the map using a ruler. Then, apply the scale to convert the measured distance to the real-world distance. For instance, if the measured distance is 5 cm and the scale is 1:50,000, the real-world distance is 5 cm * 50,000 = 250,000 cm or 2.5 km.
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Using a Graphic Scale: Simply align the ruler with the graphic scale bar on the map. Measure the distance between your two points. Then, compare this to the scale bar on the map to determine the real world distance.
Example
Let's say a map has a scale of 1:50,000. If the distance between two towns on the map is 10 cm, the actual distance is 10 cm * 50,000 = 500,000 cm = 5 km.
As noted in the provided YouTube video snippet, precise measurements can be taken. A measurement of 3.9 centimeters might equate to 4.65 kilometers depending on the scale.
Tools like the MapTools scale calculator can help in the calculations.
