Map Keys and Scales

Most maps have keys and scales that help the reader understand the map. The key explains symbols and colors used on the map, so you know what they represent. Scales tell you the relationship between the size of the map and the size of the place in real life. An image of an old map of the world.

Map Keys

Maps represent a variety of geographic information. This information might include things such as roads, tourist attractions, and campgrounds. The objects on a map are represented using symbols. A symbol is a picture on the map that represents something in the real world, like a landform.
 
Understanding these symbols requires a key. Maps use a key, or legend, to explain the meaning of each of the symbols on the map. These keys show a small picture of each symbol with a written description of its meaning.
An illustration of a map key showing tree = park, G = gas station, etc.

Map keys describe the meaning of each symbol on the map.

Map Scales 

Maps show teeny, tiny versions of places in real life. Maps of the United States are usually quite small, even though the US is actually thousands of miles long! So how can you tell how far away things really are just by looking at a map?
 
Maps use scales to show the reader the relationship between the size of the map and the size of the place in real life. When scaling down a map, every part of the map scales by the same amount. This ensures that every object on the map is the same proportion as everything else on the map.
An illustration of a map scale showing 1 : 550,000 or 9 miles to 1 inch.

Maps have scales to show the relationship between the size of the map and real life.

Notably, there are some shortcomings of scales, especially when hiking. If we’re walking across a flat plain, they’re more or less perfect. But say you’re going through a forest with lots of bends and hills. You really can’t estimate how long your path will be with just a scale, then. In that case, other features, like contour lines, are necessary for navigation.
 

Types of Map Scales

There are three main types of map scales: graphic, verbal, and fractional. Each of these methods shows the same kind of information in a different way. 
 

Graphic Scale

A graphic scale depicts scale using a line, with markers like on a ruler. There are many benefits to using a graphic scale. It is a straightforward, easy way to determine scale. Also, if a map’s size gets bigger or smaller, the graphic scale also changes size, so that it is still accurate.
The graphic scale shows a bar with colored lines depicting miles or kilometers.

The graphic scale uses a line with labels that show how big the things on the map would be in real life.

Verbal Scale

The verbal method of depicting scale uses words to describe the ratio between the map and the real world. For example, a map might say something like, “one inch equals one hundred and fifty miles.” Calculating scale on a map using the verbal method is easy. First, measure the distance on the map. Then, follow the verbal directions to calculate the actual distance.
The verbal method shows words and numbers, as in, 3 inches = 10 miles.

The verbal method writes out the conversion using words and numbers.

Fractional Scale 

The fractional method for scale uses a fraction to describe the ratio between the map and the real world. For example, let’s pretend 1 inch on the map represents 50,000 inches in the real world. The fractional scale on the map will read 1:50,000 or 1/50,000. This means that 1 unit on the map represents 50,000 units in real life. 
The fractional scale method uses a ratio, or fraction to tell you it's size.

The fractional method often looks like this, with two numbers separated by a colon.

Large and Small Scale Maps 

A map which depicts a small territory is referred to as a large scale map. This is because the area of land represented by the map has a larger scale. A large scale map only shows a small area, but shows it in great detail.
A map depicting a large area, such as an entire country, is a small scale map. To show the entire country, the map must be scaled down until it is much smaller. A small-scale map shows more territory, but it is less detailed.

Other Great Resources

Scale Facts from Kiddle Encyclopedia: https://kids.kiddle.co/Scale_(map)

Map Skills Song from Flocabulary: https://www.flocabulary.com/unit/map-skills/

Understanding Scale: https://www.gislounge.com/understanding-scale/

Written By: Leah Tolby