How to Calculate the Mileage on a Map

You can calculate the mileage on a map easily with a few basic tools

If you don't have an electronic map or GPS system providing you with everything you need to know about a given map, then you will need to acquire the knowledge by using the map's key and scale. A map's scale provides an easy method of calculating the "real-life" distance from one point to another. With a scrap piece of paper, ruler and a piece of string, you can easily determine the mileage on any map.

Instructions

1. Locate the scale on the map, usually located in one of the map's corners. This scale provides the necessary information to calculate mileage. The scale can be expressed in different ways. For example, there may be a simple equivalency statement reading, "One inch = Five Miles" or there may be a bar scale that looks like a mini ruler.

2. Locate the points on the map for which you want to determine the mileage.

3. Measure the distance between the points with a ruler if the scale is given as an equivalency statement. For example, if the equivalency statement reads "One inch = Five miles," and the distance, measured by the ruler is four inches, then the "real-life" distance would be 20 miles.

4. If the map has a bar scale, copy or trace the scale (usually marked with tick marks that equal miles; one tick mark equals one mile) onto a scrap piece of paper. Lay the paper on the map to determine the distance between points. For example, there could be a bar scale that has 0 to10 tick marks on it. This means that the length of the scale is equal to 10 miles. By placing the copy of the scale onto the map, you can calculate mileage. For example, if the distance between two points covers three tick marks on the scale, then you know that the distance is three miles.

5. If you want to calculate the mileage along a curve, place a string along the curved line on the map and mark the end point of the string by holding it between your thumb and index finger. Mark the string end points with a marker before picking it up. Pick it up and straighten the string and lay it against the bar scale to calculate the mileage. If the map uses an equivalency statement, lay the string along a ruler and determine the mileage.

References

• CUNY: Using Map Scales