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How to calculate the area and circumference of a circle

10th April, 2025

Can you remember how to calculate the area and circumference of a circle?

It is important to know how to do this for any GCSE maths paper. There are two very useful formula but they can be a little confusing to remember. To help you, I have a fun ditty that my maths teacher taught me when I was at school (many moons ago!).

Easy way to calculate area and circumference of a circle

Tweedle Dum and Tweedle Dee
Round the circle is Pi times d
If the area is to be declared
Use the formula Pi r squared

Of course, you’ve got to understand what the d and the r represent. Pi is represented as the π symbol. It can either be simplified to something like 3.14 or you can use the π button on your calculator.

Here’s a handy diagram, recapping the component parts of a circle:

Components of a circle

So in summary, these are the two formula you’d need to know for a GCSE maths exam.

Circumference of a Circle = πd

Area of a Circle = πr2

All of this can be found on a handy, FREE to download, PDF file that I have created – DOWNLOAD – How to calculate the area and circumference of a circle.

Nicola Bhalerao - Warwick Tutor

About Me

My name is Nicola Bhalerao and I am a private tutor based in Warwick. Since 2013, I have provided one-to-one tuition for children and adults. I specialise in maths tutoring, but cater for different requests, ranging from 11+ / entrance exams to various uses of maths, e.g. : interviews, job promotions, GCSE retakes, Functional Skills, nursing, teaching – any situation where confidence in maths is required.

My background is in computing, with a Computer Science degree from Warwick University. I have worked many years as a programmer, latterly in the games industry. Both my sons were tutored by me for the 11+ (they went to a local grammar school). I received training for teaching secondary school maths and I am fully CRB checked.

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