Line Graph – Definition with Examples

What is Line Graph?

line graph is a type of chart used to show information that changes over time. We plot line graphs using several points connected by straight lines.  We also call it a line chart. The line graph comprises of two axes known as ‘x’ axis and ‘y’ axis.

  • The horizontal axis is known as the x-axis.
  • The vertical axis is known as the y-axis.

Parts of a Line Graph

The given image describes the parts of a line graph.

Title: tells about the data for each line graph is plotted.

x-axis: tells about labels on x-axis, which is generally time.

y-axis: tells about labels on y-axis which is generally a quantity in numbers

Trend: We join the points to draw the graph. The intersection point of the label on the x-axis and y-axis tells about the trend. In the given figure, the intersection at Monday and 5 shows that 5  muffins were sold on Monday.

line graph

Plotting a Line Graph

Plotting a line graph is easy. Here are the simple steps to consider while plotting a line graph.

  • Draw the x-axis and y-axis on the graph paper. Make sure to write the title above the table so that it determines the purpose of the graph.
  • For instance, if one of the factors is time, it goes on the horizontal axis,  referred to as the x-axis. The other factor would subsequently go on the vertical axis, which is known as the y-axis. Label both the axes as per their respective factors. For example, we can label the x-axis as time or day.
  • Afterward, with the help of the already given data, point out the exact values on the graph. Once you join the points, you can make a clear inference about the trend. 

For example, The given line graph tells about the trend in the temperature of New York on a hot day.

example of line graph

Reading a Line Graph

Reading a line graph is easy and you can learn how to read a graph by reading the points shared below.

  • First, take a look at the two axes and try to understand what these axes denote.
  • Then look at the graph and examine the values of the points situated in the lines of the graph.
  • Follow the lines and figure out if there is any kind of rise or fall. Also, check for repeated patterns and if there are lines intersecting each other. This way, you will get to know the purpose of the line graph.
  • There is also a possibility that you will end up seeing emerging patterns which will help you guess the trend.

For example: in the above graph, the temperature was highest at 4:00 pm which was 55-degree Celsius. Read the above graph and answer the following questions:

  A: What is this graph about?

  B: When was the temperature minimum?

  C: What was the temperature at 3:00 pm?

Fun Facts about Line Graph
– The initial line graphs were made by various persons namely Nicolaus Samuel Cruquius, Francis Hauksbee, William Playfair, and Johann Heinrich Lambert.

Practice Problems

Line Graphs

Attend this Quiz & Test your knowledge.

1In a particular line graph, the x-axis represents the month number and the y-axis represents savings in a month in dollars. What does the point (4, 10) on the line graph represent?

Savings of $10 in the month of April.
Savings of $4 in the month of October.
Savings of $10 in the month of October.
Savings of $4 in the month of April.
Correct answer is: Savings of $10 in the month of April.
For the point (4, 10): 4 represents the month number, and 10 represents the savings in a month in dollars. Therefore, (4, 10) represents a saving of $10 in the 4th month, i.e., April.

2If a line graph is a straight line parallel to the x-axis, then, which of these points will NOT lie on it?

Correct answer is: (3,0)
The point (3,0) will lie on the x-axis and not on a line parallel to the x-axis.

3A line graph makes the use of:

Circular chart
plotted lines
Correct answer is: plotted lines
A line graph makes the use of plotted lines, whereas a pie chart uses a circular chart. Bars are used in Bar graphs, and pictures/images are used in picture graphs to represent data.

4A line graph is NOT used to:

track changes over a period of time
compare parts of a whole
understand trends in temperature over months or years
observe similarities and differences between trends of rainfall change in 2 cities
Correct answer is: compare parts of a whole
A line graph is not used to compare parts of a whole. A pie chart is most suitable for that.

Frequently Asked Questions

Yes, there can be more than one line in a line graph. This is usually done when we need to compare two sets of information represented by each line.

Line graphs are used to track changes over short and long periods. Line graphs are useful to study or represent temperature, rainfall, the revenue of a company, etc.

No. The line formed by joining all the data points in a line graph may or may not be straight. The line graph with a straight line is called a linear graph.

A double line graph is a type of line graph that represents two sets of data or information in a single graph. It is mainly used when we need to compare two sets of information and make inferences.