How to find percentages for a pie chart

Question

This pie chart calculator quickly and easily determines the angles and percentages for a pie chart graph.

Table of Contents Show

How to Calculate Percentages for a Pie Chart
How to Calculate Pie Chart Angles
Short Cut Method
About This Article
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What is 25% on a pie chart?

Simply input the variables and associated count, and the pie chart calculator will compute the associated percentages and angles and generate the pie chart.

How to Calculate Percentages for a Pie Chart

Pie charts are visual representations of the way in which data is distributed. Through the use of proportionally sized slices of pie, you can use pie charts to provide accurate and interesting data insights.

Step 1

The first step involves identifying all the variables within the pie chart and determining the associated count. For instance, let's say we are interested in the expenditure of four companies: A, B, C, and D. Let's say the expenditure is as follows: A is $2000, B is $1500, C is $3500, and D is $3000.

Step 2

Sum the four values you identified in Step 1 as follows:

$2000 + $1500 + $3500 + $3000 = $10000

Step 3

Divide each company total by the sum identified in Step 2 to determine the percentage of total revenue as follows:

A: (2000/10000)(100) = 20%

B: (1500/10000)(100) = 15%

C: (3500/10000)(100) = 35%

D: (3000/10000)(100) = 30%

By generating a pie chart based on this data, you can gain insights into how each variable within the total pie is representative of the sum of the pie.

How to Calculate Pie Chart Angles

The distribution of data within pie charts is displayed in sections that are proportional to the sum of the total objects in the group. To accurately draw a pie chart, you need to identify the angle for each section within the pie. You can do this as follows:

Step 1

For each variable you wish to represent in the pie chart, identify the number of people, objects, or value. For instance, let's say a newspaper subscriber list is separated into three distinct categories: A, B, and C, with the count being as follows: Category A, 1200 people, B 750 people, and C 250 people.

Step 2

Add the total number of people identified in Step 1 to give you the total number of people.

As such, in our example we have the following:

1200 + 750 + 250 = 2200 people.

Step 3

Divide the count for each variable by the total count and then multiply this figure by 360 to determine the angle in degrees.

As such, in our example, we have the following:

A: (1200/2200)(360) = 196.36°

B: (750/2200)(360) = 122.72°

C: (250/2200)(360) = 40.9°

When the pie chart is drawn, the slice of pie for Group A will have an angle of 196.36°; as such, it will represent just over half of the full circle. The slice of pie for Group B will measure 122.72°, which is equivalent to just over a quarter of the circle. The slice of pie for Group C will measure 40.91°, which is equivalent to around one-fifth of the circle.

Short Cut Method

An alternative method of determining the pie chart angle is by multiplying the percentage by 3.6. For instance, Group A represents 54.55% of the total pie. Since (54.55)(3.6) = 196.3, this generates an angle of 196.3°.

A pie chart, which looks like a divided circle, shows you how a whole object is cut up into parts. Pie charts are most often used to represent percentages. For example, the following figure is a pie chart representing Eileen’s monthly expenses.

You can tell at a glance that Eileen’s largest expense is rent and that her second largest is her car. Unlike a bar graph, the pie chart shows numbers that are dependent upon each other. For example, if Eileen’s rent increases to 30% of her monthly income, she’ll have to decrease her spending in at least one other area.

Here are a few typical questions you may be asked about a pie chart:

Individual percentages: What percentage of her monthly expenses does Eileen spend on food? Find the slice that represents what Eileen spends on food, and notice that she spends 10% of her income there.
Differences in percentages: What percentage more does she spend on her car than on entertainment? Eileen spends 20% on her car but only 5% on entertainment, so the difference between these percentages is 15%.
How much a percent represents in terms of dollars: If Eileen brings home $2,000 per month, how much does she put away in savings each month? First notice that Eileen puts 15% every month into savings. So you need to figure out 15% of $2,000. Solve this problem by turning 15% into a decimal and multiplying:
0.15 2,000 = 300
So Eileen saves $300 every month.