Determine the scale of the map. This number is expressed in ratio format and on either the map's bottom right side or cover. An example of a map ratio, or map scale, is 1-to-10000, which may be printed as 1:10000. This ratio signifies that every 1 inch on the map is 10,000 inches in reality.
Locate on the map the starting point and end point of a distance you want to calculate. Look for landmarks close to the starting point and end point to help guide you. If you know the end point is near a specific shopping mall, for example, then locate the mall on the map, and then scan near it for your desired end point.
Place the starting edge of a ruler exactly at the starting point you found on the map. Pivot the ruler to allow it to run directly, in a straight line, to the end point on the map. Note the measurement on the ruler between the starting point and end point.
Convert the scaled-down measurement that you determined using the ruler into actual distance by multiplying it by the larger number in the map scale, or map ratio. If you measured 2 inches on your map using the ruler and the map ratio is 1-to-10000, for instance, then you would multiply 2 by 10,000. The resulting figure is the actual distance between the starting point and end point.
