📊
Statistics & Probability · Foundation & Higher

Pie charts

Pie charts show data as sectors of a circle. Each sector's angle is proportional to the frequency. You need to draw and interpret pie charts.

🔑

Key facts to remember

  • 1The total of all frequencies corresponds to 360°.
  • 2Angle for each category = (frequency ÷ total) × 360°.
  • 3To find a frequency from a pie chart: (angle ÷ 360°) × total frequency.
  • 4Use a protractor to draw and measure angles accurately.
  • 5Label each sector with the category name (not just the angle).
📐

Formulas

Sector angle
Angle = (frequency / total) × 360°
Frequency from angle
Frequency = (angle / 360°) × total
✍️

Worked examples

Example 1

60 students were asked their favourite sport. 15 chose swimming. Find the angle for swimming in a pie chart.

Working

  1. Angle = (15 ÷ 60) × 360°
  2. Angle = ¼ × 360° = 90°
Answer90°
Example 2

A pie chart sector for "cycling" has an angle of 72°. The total is 150 people. How many chose cycling?

Working

  1. Frequency = (72 ÷ 360) × 150
  2. = 0.2 × 150 = 30
Answer30 people
⚠️

Common mistakes

✗Using the percentage directly as the angle (e.g. 25% → 25° instead of 90°).
✗Angles not summing to 360° due to rounding — check and adjust the last sector.
✗Not using a protractor and drawing sectors by estimation.
🎯

Exam tips

✓Always check your angles sum to exactly 360° before drawing.
✓Show the calculation for each angle in your working — examiners award method marks.

Ready to test yourself on Pie charts?

Get AI-marked practice questions on exactly this subtopic.

Practice this topic →
← All topicsDashboard

▶️ Watch on YouTube

Free video lessons

Click a topic to search

▶pie charts GCSE maths▶drawing pie charts GCSE▶pie chart angles GCSE maths▶interpreting pie charts GCSE Foundation

Opens YouTube — pick any free GCSE video.