Geometry Calculators

Circle Calculator

Enter radius, diameter, circumference, or area to calculate the main circle measurements with step-by-step work.

Geometry Formulas Sheet r h

Direct answer

What does the circle calculator solve?

The circle calculator solves radius, diameter, circumference, and area from one known circle measurement. It uses formulas such as , , , and , then shows the substituted values and steps. Use it when only one circle measurement is known.

Quick formula table

Calculator formulas

CalculatorFormulaWhat it finds
CircleArea
CircleCircumference
CircleDiameter

Calculator

Circle Calculator

Results include the answer, unit, formula, and calculation steps.

Enter values and select Calculate to see the result, formula, and steps.

Formula reference

Related formula pages

FAQ

Circle Calculator FAQ

Can the circle calculator use diameter?

Yes. Select diameter as the known measurement and enter the value.

What formula does it use for area?

It uses .

What formula does it use for circumference?

It uses and .