"Hey Lulu, I got a map! How about my trotting over from Louberg to visit you in Luluville?! How long will it take me?"
"Love you to, Lou! But I can't tell you how long it'll take! For one thing, there's nothing on the map to tell me how far it is between Louberg and Luluville. Or between any other two places! Your map needs a scale!"
"What's a scale?"
"A scale is something that tells you how the distance on the map compares to the distance on the ground. Take a look at my copy of your map! It has three different ways of giving the scale!"


commonly written as
One unit of length on the map represents 500,000 of that same unit on the ground. For example, 1 inch on the map = 500,000 inches on the ground. One cm on the map represents 500,000 cms on the ground. And so on.
STATEMENT OF EQUIVALENCYOne inch = 7.9 milesIt may be useful to know how many miles on the ground one inch on the map represents. For this map, the R.F. is 1/500,000, so 1 inch on the map = 500,000 inches on the ground. To find out how many miles 500,000 inches equals, divide 500,000 inches by 63,360 inches per mile. The answer is 7.89 miles (or approximately 7.9 miles). So, one inch on the map = about 7.9 miles on the ground.
Similarly, to find out how many kilometers on the ground 1 cm on the map represents, divide 500,000 cms by 100,000 cm per km. The answer is 1 cm on the map = 5 km on the ground.
BAR SCALEA bar scale is a graphic representation of distance. It shows, visually, what distance on the map represents a unit of distance on the ground. In this case, the distances on the map that represent miles and kilometers are shown.
"To learn how to use map scales, Lou, go to 'Distance' and click on 'Using Scales'!"

© 2010
David J. Leveson/Revised by G. Rocha and Michelle O'Dea