In order to measure distances and locations on the Earth's surface, scientists use a system of imaginary lines called latitude and longitude. Longitude runs north and south and is used to measure distances that are east and west. Alternatively, latitude runs east and west and is used to measure distances that are north and south. Because of the Earth's curvature, lines of latitude are equidistant to each other (as opposed to the curved lines of longitude). As such, it is easy to convert latitude into miles.
Divide the amount of miles by the degrees in a circle. The circumference of the earth along the equator is 24,901.92 miles, and there are 360 degrees in a circle. This results in about 69.2 miles. That is the approximate distance between each degree of latitude.
Find the two points of degrees of latitude that you are measuring. In this example, our longitude points remain the same because we are only dealing with latitude.
Find the amount of degrees between the two points. Keep in mind, lines of latitude south of the equator will be listed as negative lines, meaning you need to use the absolute value of the lines. Let's say we're finding the distance between 20 degrees north and -10 degrees south. That is a total of 30 degrees.
Take the amount of degrees and multiply it by 69.2 miles, which we found in Step 1. For our example of 30 miles, you have a distance of 2,076 miles.