What is a Bar Graph?

Bar graphs are one of the best ways to show a lot of data all in the same image. It is a simple way to show different kinds of data, changes in data over time, or compare lots of things all on the same chart. It is easy to learn, especially when you learn the key parts.

(You can also watch the video at the end of the page!)

Every bar graph has a few common parts:

Let’s break down each part:

Every single graph should have a title. Bar graphs are the same. They are simple to read, but if the graph doesn’t have a title, you’ll be lucky to understand what it’s about. A title should be a summary of the data shown. The title should say what is being measured. Good titles will often have other information. Some times this secondary information will be in parentheses.

For instance, the title of your bar graph could be “Sales”. This shows that the information below will explain the amount of sales. A better title would be “Car Sales”. This shows that you are measuring the sales of a specific product, cars. An even better title would be “Car Sales (Europe & Asia)”. This shows that you are measuring car sales in two specific regions of the world.

The horizontal axis of a bar graph is the line going from left to right, typically at the bottom of the graph. It should have labels at each step along the graph that define what information is being shown. The horizontal axis of the bar graph can be tricky. Bar graphs can show lots of information, which means that each horizontal axis is different.

Horizontal axes can show movies, cars, colors, anything! The key thing is that you need to show the units. If you don’t write out what each graph is, no one will know. Showing the units is important.

Here are a few examples.

The vertical axis of a bar graph is the line going up and down, typically on the left side of the graph. This axis is counting objects. It will have many measurements marked along it, going from small to large. Each vertical axis will look different. Some will count by ones, some by fives, some by tens, some by hundreds, etc. The key information is that you know where to look to find the total number of objects. As always, the units must be included to give full understanding.

Here are a few examples.

Every graph should have a key (sometimes called a legend). The key shows what each bar is displaying. If there are multiple patterns or colors of a graph, they key is where you tell what each color represents.

The key (legend) is shown in the images below.

Bar graphs help count things. They can count small numbers and large numbers. They show comparisons between things. It is a very easy way to show a comparison. When you learn the parts of a bar graph, you’ll learn that they are easy to read and easy to use.