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Calixo

Circle Calculator

Find the area and circumference of a circle from its radius.

Inputs

Saved Scenarios

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Area

78.54

Circumference

31.42

Spark says

How it's calculated

Formula

Area=πr2Circumference=2πrArea = \pi r^2 \quad\quad Circumference = 2\pi r
r
— Radius

What is the Circle Calculator?

This calculator finds a circle's area and circumference (perimeter) from its radius, using the constant π.

How to use it

  1. 1 Enter the radius.

Worked examples

Radius 5

Area is about 78.54, circumference is about 31.42.

Try it

Frequently asked questions

How do I use diameter instead of radius?

Divide the diameter by 2 to get the radius, then enter that value.