Pie Charts. Working Out The Angles in a Pie Chart. An Easy Method by Working Out The Angle For 1 Person in 1 Pie-Charts.

There are quite a few steps involved when drawing a pie-chart, but the most important step is working out the angles. To work out the angles needed to draw a pie-chart follow these steps:

STEP 1 Add up all the people in the survey.

STEP 2 Divide 360 by the total amount of people in the survey. This will tell you the angle required for 1 person in the survey. Try remembering the rule:

Angle for 1 person = 360 ÷ total amount of people

STEP 3 Now since you know the angle for 1 person, you can multiply the number of people in each category by this number to give you all of the angles.

When you have worked out all of the angles you can measure all the angles on your pie chart with your protractor. The circle is usually drawn in test situations, but if it’s not then draw the circle using a compass and mark in the radius so you can measure your first angle from this line.  It’s probably best to measure the smallest angles first. Once the angles are measured make sure you write in all the angles at the centre of your pie chart and label all of the sectors with each category (or use a key and colour it in – but this will be more time consuming if you are drawing a pie chart in your exam).

Let’s take a look at an example:

Example 1

In a survey on favourite school subject:

18 people voted Math (always the favourite)

12 people voted Chemistry.

10 people voted History.

Work out the angles need for each category in order to draw a pie-chart.

Step 1:

Add up all the people in the survey.

18 + 12 + 10 = 40.

Step 2:

Angle for 1 person = 360 ÷ total amount of people

360 ÷ 40 = 9⁰

Step 3:

Multiply all the categories by 9⁰.

Math = 18 × 9 = 162⁰

Chemistry = 12 × 9 = 108⁰

History = 10 × 9 = 90⁰

You can always check that all the angles add up to 360⁰ and this will confirm all the angles are correct:

162⁰ + 108⁰ + 90⁰ = 360⁰

So all the angles have all been calculated correctly.

For some more examples on calculating the angles in a pie-chart click here.

Or for some harder examples click here.