Circle Calculator

Solve the main circle measurements from whichever single circle value you already know.

Preparing Circle Calculator

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Input

Start with the circle value you know, whether it is radius, diameter, circumference, or area, and the calculator will find the rest. You will see the result first and the step-by-step solution below.

Input summary

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Step by Step Calculation

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Step by step calculation shows here

Calculate first and the full working will appear below automatically.

How to use Circle Calculator

Choose the starting measurement, enter it once, and the calculator will convert that one circle value into the other standard circle measures.

What this calculator is for

This calculator is for geometry review, drafting, and everyday measurement problems where one circle value is known and the remaining measurements need to be derived quickly.

Tips

Do not mix up radius and diameter; diameter is twice the radius.
Circumference is a linear measure, while area is square measure.
Keep the unit consistent so every derived circle value stays in the same measurement system.