What Is a Line Graph? Definition and How To Create One

By Indeed Editorial Team

Updated October 17, 2022 | Published January 3, 2020

Updated October 17, 2022

Published January 3, 2020

The Indeed Editorial Team comprises a diverse and talented team of writers, researchers and subject matter experts equipped with Indeed's data and insights to deliver useful tips to help guide your career journey.

Image of sample line graph

A line graph is a visual tool that can companies in any industry can utilize to show the value of something over time. Line graphs are common in finance and marketing, but they also work well in weather monitoring and laboratory research. If you work in any of these fields or want to improve your data and presentation skills, you can benefit from using properly formatted line graphs.

In this article, we review what line graphs are, explain how to create one and share ways to use them in your career.

What is a line graph?

A line graph is a type of chart that displays how the value of an item changes over time. Line graphs, also known as line charts, can have multiple lines on the same axis, which readers typically compare to one another. For example, you can create a line graph showing the difference in profits that each department makes in a company. Each department can have its own line with its own color, and a legend on the graph can explain which colors correspond to which lines. Line graphs typically have two axes:

  • X-axis: The horizontal line at the bottom of the graph. This typically involves time references, like dates, months or years.

  • Y-axis: The vertical line on the left side of the graph. This typically involves other data points, like sales figures or quantities.

The x-axis is an independent axis, as the values are not dependent on anything. For example, units of time usually appear on this axis, since time always moves forward regardless of other factors. The y-axis is the dependent axis because its values depend on those on the x-axis. Every x value only has one y value, which leads to a line that progresses horizontally. For example, one company can only have one amount of money on a certain date.

Related: How To Change Y-Axis Values in Excel (2 Methods) 

How to create a line graph

A line graph can help you analyze information that has connections in some way. Follow these steps to create an effective line graph:

1. Make a table

First, choose the way you intend to create your table. You can use various tools, like spreadsheet software or word-processing applications. You can also try using online applications to make your table. For a low-tech approach, try using paper to create a table manually. 

Once you've chosen your method, create a table that has the values for the x-axis and the y-axis. Then add a title at the top of the page to explain the topic of the graph you plan to make using your table.

Related: 17 Common Types of Function Graphs and Their Formulas

2. Label the axes

If time is a factor in your line graph, put it on the x-axis. Any other numeric values go on the y-axis. Each axis might have a label with the numeric system that you can use along with what measurements are used. If money is one of your factors, make sure to indicate what type of currency it's in. If time is a factor, specify whether you're analyzing it in hours, days, months or another unit. This can make a difference in how people read your graph. You can put “Time (months)” so it's simple and clear. It can be best to evenly divide sections into the appropriate increments.

Related: A Guide to Funnel Charts

3. Add the data

There are usually two columns in a table used for the data in the line graph that correspond to the two axes. For example, you might have sales figures for each month in your table. Some tools, like spreadsheets, can automatically generate a graph from the data in your table. If you create a line graph manually, you can plot your data directly on the graph with the corresponding information from your table.

4. Make a key

When comparing different items, you can create a form that shows each line in a different color so it's easy to distinguish between different data sets. A key helps people reference the color or style of each line to understand what they represent. For example, you might have long dotted lines for one department and shorter dotted lines for another. Consider clear labels in the key so the graph is easy to understand.

If you're using a spreadsheet application, you only need to take a few steps to create a line graph. Select all the data you have in your table and click Insert and then there could be an option to select a chart. Sometimes you can change the type of chart by seeing if there is an option to change your chart type.

Related: 10 Tips for Giving a Great Presentation

Line graph uses

Line graphs are popular to use in a variety of settings. Here are some of the key uses for line graphs:

Translate information

One of the main reasons why people use line graphs is because they're easy to read. Companies often capture a lot of information in databases or spreadsheets. By creating a line graph, you can present the information in a new way, helping for people to understand the data easier.

Related: What Is Data Visualization? Types, Uses and Tips

Compare data points

Line graphs can also be useful to indicate and explain multiple data points. For example, consider a graph showing the difficulty of performing daily activities based on an individual's age. You can place ages on the x-axis, start at 65 years old and go to 85 years old and beyond. The y-axis could contain the percentage of difficulty for each activity. There are six different lines to represent the various activities, including eating, showering, dressing, getting in or out of bed, using the toilet and walking. Each line is a different color, and a key sits on the right side of the graph explaining what color line represents what activity.

Understand trends and relationships

Line graphs are helpful tools that help readers understand data points. They make it easy to review the trends in data without needing to explain much to the person reading the graph. Line graphs are also useful when tracking multiple lines to see how they relate to each other and if there are any obvious trends in a larger data set. Knowing how to create a line graph makes it easy to display the research you have done and explain it to others.

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