Revising pie charts the night before an exam? These are condensed revision notes — the facts, formulas and mistakes examiners actually mark, with no long explanations. Prefer a full walkthrough with step-by-step reasoning instead? Search “Pie charts GCSE” on the site for the complete guide.
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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).
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Formulas
Sector angle
Angle = (frequency / total) × 360°
Frequency from angle
Frequency = (angle / 360°) × total
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Worked examples
Example 1
60 students were asked their favourite sport. 15 chose swimming. Find the angle for swimming in a pie chart.
Working
Angle = (15 ÷ 60) × 360°
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
Frequency = (72 ÷ 360) × 150
= 0.2 × 150 = 30
Answer30 people
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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.
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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.
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