Although incredibly useful, maps would have no meaning without a set of symbols and rules by which to read them. In this lesson, you will learn about map scale, the different types of scales, and a few examples of how they work.
Definition of Map Scale
Imagine you just moved into a new house or apartment. You take a trip to the nearest furniture store and buy a few storage shelves to put up so you can display all of your prized possessions. You get the boxes home, open them up, and lay out the pieces of the shelves. You find all of the nuts and bolts you will need and then discover quickly that something is very wrong. There are no instructions in the box! Somehow, the instruction page was left out of your box and you have no idea how to put the shelves together.
Without the proper guidance, even a simple task can become impossible.When reading a map, you need to refer to a set of instructions in order to understand distances in real life. A map scale is a ratio of the distance on a map to the actual distance of the ground.
Map scales can usually be found on the outer edge of a map, usually near the map’s key (a set of symbols that also make the map easier to understand). Whether the scale is drawn out or written, you can easily calculate distances if you know the ratio.The map scale on most maps is quite a large ratio. After all, maps are a physical representation of the Earth. In order to have a 1:1 ratio of map to ground, you would have to carry around a map as big as the planet! Pockets are usually not big enough.
Types of Map Scales
There are two main types of map scales: bar and lexical.
In a bar scale, which tends to be the most common, the mapmaker has given you a visual guide to use to make distance calculations. You can use any measuring tool or a piece of string to figure out actual distances on a map by directly measuring the map distance and translating it to the bar scale.A lexical scale is not visual like a bar scale. Instead, the mapmaker gives the distance conversion in words. For example, the map may include the scale written as ‘1 inch equals 10 miles’. This is generally viewed as less practical and is, therefore, much less common.
With this scale, it is also much more common to run into language barriers for speakers of languages other than what the map is written in. This scale works in the same way as the bar scale, but it is just represented differently.
Examples of Map Scales in Use
Let’s look at some real world applications that could actually help someone trying to gauge distance in their day-to-day lives.
First, we have a map of the Washington DC metro system drawn to scale.
On the Washington DC Metro map, the map scale is in the lower right-hand corner. It gives distances in kilometers and miles. For this example, we’ll use miles. If someone wanted to travel on the Red Line from Rockville to the Metro Center, he could figure out the distance by measuring how many times the map scale distance is traveled. A piece of string works well for this task.
This trip travels a little over 3 times the distance of the scale. Since the scale tells us this distance is 5 miles, we can approximate the distance at about 16 miles.
On this map of Bali, the map scale is in the lower left-hand corner. It is given in meters and miles, but we’ll use miles. The distance on this scale is much less than the DC Metro map’s scale because the map is detailing a much smaller area.
Using the same method as before we can figure out the distance from Waroeng Asia (Number 8 on the food guide) to Bali Beach Shack (Number 1 on the food guide). It measures out to be about 4 of the units given on the map scale, or 0.8 miles.
This would be useful if you were visiting Bali and wanted to walk from one point to another.
Just as it is important to have a set of instructions when building a piece of furniture, it is necessary to have a map scale when reading a map in order to calculate accurate distances in real life. There are two types of map scales, bar and lexical, but bar scales are used more frequently because they represent the distance ratio visually instead of in words, as is the case with lexical scales. Using map scales is important in the real world if you want to figure out the distance you are traveling.
Points to Remember
- A map scale shows the ratio between distances on the map and distances in real life
- A map scale can be a bar scale (visual) or a lexical scale (written words)
- Map scales are useful in determining the real-life distance between points on a map
Once you are finished, you should be able to:
- Explain what a map scale is used for
- Describe the two types of map scales
- Estimate the distance on a map using the map’s scale