Pie Chart

A pie chart is a circular graph in which each slice represents the share of the total for its category. The pie chart represents 100% of the data, with each slice proportional to its percentage of the total. Pie charts are used to visualize data such as market shares, survey results, and budget allocations.

The pie chart above shows the distribution of different fruits preferred by a group of people. Each slice represents the number of people who chose a particular fruit. The fruits included are Mango, Orange, Pineapple, Melon, and Plum.
 

According to the data from the pie chart:
 

• Mango: 108 people. 
• Orange: 72 people 
• Pineapple: 72 people
• Melon: 72 people
• Plum: 36 people

From the pie chart, we can understand which fruit is the most and least preferred:
For example, the largest sector is for mango, so mango is the most preferred fruit. The smallest sector is for plum, so plum is the least preferred fruit. Orange, pineapple, and melon each have 72 people, showing that they are equally popular. 

This pie chart helps to: 

• See how the total number of people is distributed among different fruits.
• Compare preferences quickly by looking at each slice's size.
• Understand which fruits are more or less prevalent in the group.

Importance of Pie Chart

 

• Pie charts are essential for students, as they visually simplify data distribution and proportions.  
   
• They make complex information easier to compare and are useful in subjects like mathematics, statistics, economics, and science.

• Using color to identify each division helps students improve their interpretation skills and understanding of fractions and percentages. 

What is a Pie Chart Used For?

A pie chart is primarily used to show how a whole is divided into parts. In simple words, it visualizes the part-whole relationship. Here are some common uses of pie charts.
 

• Showing proportions or percentages: Each slice of the pie represents a category’s share of the total.
   
• Comparing the contributions of categories: Pie charts make it easy to see how much each category contributes to the whole.
   
• Visualizing categorical data: When you have distinct categories, such as customer types, sales by region, etc., a pie chart can help simplify how each category fits into the total.
   
• Showing proportions of summed values: Not just counts, you can use pie charts to show how sums (like total revenue) split across categories.
   

A pie chart represents the whole dataset as a complete circle. Since a full circle measures 360°, the entire set of information must also add up to this value. Similarly, when expressed in percentages, the whole circle corresponds to 100%.
Since every category in a pie chart must be shown as a part of the whole, we rely on two key formulas to convert raw data into percentages or angle measures.
 

• To find what percentage of the whole a category represents, the formula is,
  Percentage = Frequency/Total frequency ×100
   

• To translate that part of the data into a slice of a pie chart, the formula is,
  Angle of slice (°) = Given data for category/total data ×360∘.

These formulas are beneficial in many things, including:

• Understanding the share of each category out of 100%.
• Percentages make comparisons easier.
• Once the percentage is found, it can be converted into an angle for the pie chart.

Pie charts have several properties. The main properties of the pie chart are:
 

• Circular Shape: A pie chart is always a circular graph that represents the whole (100%), which is divided into sections or slices.

• Sections (Slices): The circular graph is divided into slices or sections, where each slice or section represents a category’s proportion of the total.

• Proportional Representation: The size of each section or slice is proportional to the value or percentage it represents in the whole data set.

• Angle Measurement: Each slice or section is calculated using the formula:
  Angle = Category Value / Total Value x 360°
  
   
• Percentage Values: Pie charts usually display percentages within or near slices to indicate the proportion of each category.
   

Creating a pie chart involves several clear steps, from preparing your data to drawing the final chart. The following is the structured process for creating a pie chart. 

 

Step 1: Prepare your data.
Collect and categorize your data; start with a list of categories (e.g., apples, oranges) and their corresponding numerical values.
 

Step 2: Calculate the total.
Add up all the numerical values to find the sum that your percentages will be based on.
 

Step 3: Convert data to percentages or angles.
Compute the percentages using the formula:
Frequency/total frequency ×100.
Since the whole pie is 360°, map each category to an angle using the formula:
Angle of slice = category value/total data × 360∘ 
 

Step 4: Draw the pie chart.
Draw a circle using a compass or a drawing tool of your convenience and mark the radius. 

Step 5: Construct each slice one at a time.
For each category, draw slices using a protractor or any other tools, corresponding to its calculated angles. Work in a consistent order, either clockwise or anticlockwise, to draw the slices.
 

Step 6: Format and label the chart.
Add colors or shading for each slice. Also, write the category name, its percentage, or value near each slice. Besides, include a legend. When there are many slices, a legend helps to identify which color or pattern corresponds to which category.
 

Step 7: Review and refine.
Make sure the labels are clear, slices aren’t too small, and everything sums to 360°.
 

Advantages: 
 

• Simple and easy to understand: Great for displaying basic data at a glance.
• Shows proportion clearly: Helps visualize how each part contributes to the whole.
• Visually appealing: Works well in presentations and reports.
• Good for showing percentages: ideal when the total is 100% and the categories are limited.
• Highlights major contributors: Larger slices stand out easily.

Disadvantages: 
 

• Not suitable for large datasets: Too many slices make the chart cluttered and confusing.
• Hard to compare slices: Comparing similar-sized sections can be difficult.
• Precise values cannot be shown: Pie charts show general proportions, not exact numbers.
• Not effective for changes over time: Pie charts cannot track trends or variations.
• Requires accurate angle calculation: Incorrect angles can misrepresent data.
   

There are several ways to master pie charts. Let’s learn some tips and tricks:
 

• Understand the basics: Students should remember that a pie chart represents 100% of a dataset, with each section or slice showing a category’s proportion. The total of all angles in a pie chart is 360°.

• Calculate angles correctly: Students must remember the formula that is used to determine each section's angle:
  Angle = Category Value / Total Value x 360°.
  They must always check that the sum of all the section angles equals 360°.

• Convert data into percentages: Students must be able to convert the given data into percentages for a better visual representation. They must ensure that the total of all percentages adds up to 100%. The formula used to convert data into percentages is mentioned below:
  Percentage = Category Value / Total Value x 100.
  
   
• Start with the largest category: Plot the most significant section first. This makes the chart easier to read and reduces mistakes.
  
   
• Use labels and legends properly: Always label each slice, or use a clear legend, to avoid confusion when interpreting the chart.
  
   
• Encourage real-life examples: Parents and teachers can ask students to create pie charts from everyday life, such as favorite fruits, time spent on activities, or classroom survey data.
  
   
• Use visual tools: Provide paper circles, colored pencils, or digital tools (Google Sheets, Excel) to practice creating pie charts.
  
   
• Focus on interpretation: Parents and teachers can help students understand what the chart shows, rather than just teaching them how to draw it. Ask students questions like “Which section is the largest?” and “What does this slice represent?” 
  
   
• Break the data into simpler parts: If you find students are struggling with the concept, simplify the data first and gradually increase the complexity.
   

Pie charts help us to get a visual representation of the data. Let us learn how pie charts are used in different fields. 
 

• Business and Marketing:
  
  Companies use pie charts to illustrate the market share of different brands or products. Businesses use pie charts to analyze product sales across regions or countries.
   
• Finance and Economics:
  
  Pie charts are commonly applied in budget distribution, revenue analysis, and tax allocation.
   
• Education and Research:
  
  We use pie charts for survey results, analyzing subject-wise marks or student performance, and representing student distribution by gender, courses, or departments.