What are scales useful for?

When distances in a map, in a plan or in a picture are directly proportional to the real distances, we say that the map, the plan or the picture were made “on scale”. In this case scale means the constant of proportionality. If maps did not have scales, it would be impossible to calculate the distances between two points.

Are there several types of scales?

There are three types of scales: the natural ones, the reduced ones and the enlarged ones. According to the natural ones, the distances in the picture are exactly the same as the real distances; the reduced scales (which are often used in maps and plants) are the ones which represent the size of an area bigger than the one that would not fit the picture); the enlarged scales (used to enlarge very small objects) represent a size bigger than the real one, stressing the small details. We will show an example of a map which was built according to a reduced scale.

How do you read a scale?

According to the above picture it is possible to see a map of the Iberian Peninsula. On the right inferior corner there is a graphic scale which could be converted into a numerical scale, in which we use two numbers that are separated by “:”, where the proportion of the scale is represented. In this map, the numerical scale would be 2 cm : 190 km, and if we wanted to simplify so as to obtain the same measuring unit, we would get: 2:19.000.000, however, the most common situation is to write number 1. So, the scale would be: 1:9.500.000. The left number represents the distance in the map, while the right one stands for the real area we want to represent. Thus, we mean that 2 cm in the map corresponds to 190km in reality. If we want to know the distance between Madrid and Barcelona, you just have to have a ruler and then measure the length (in cm) from the red line that joins the cities and then multiply by 95 (1 cm corresponds to 95 km), and you will get the real distance in km.

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