How to explain circumference in circumference, area & parts of circles to your child
27 October 2026
Understanding the circumference of a circle is an important part of 11+ maths. If your child knows the diameter, they can use a simple formula to work out the distance around the edge of the circle.
Worked example
Find the circumference of a circle with a diameter of 10 cm.
Step 1: Use the formula for circumference. Circumference = π × diameter.
Step 2: Put in the diameter. Circumference = π × 10 cm.
Step 3: Use π ≈ 3.14. Circumference = 3.14 × 10 cm = 31.4 cm.
The answer is 31.4 cm.
After seeing this example, your child should be able to spot the diameter in a question and use it to find the circumference. Practise with similar questions will help them feel confident with this type of problem.
