Circle Calculator
Area, circumference, diameter and arc length from any one value.
Area
78.539816cm²
Radius
5cm
Diameter
10cm
Circumference
31.415927cm
ShowHide the working
- 1Radius = 5 cm
- 2Area = π × 5² = 78.539816
- 3Circumference = 2π × 5 = 31.415927
Formula
A = πr², C = 2πrHow it works
Give any one measurement of a circle and the rest follow.
Example
A radius of 5 gives an area of 78.54 and a circumference of 31.42.
About the Circle Calculator
Area, circumference, diameter and arc length from any one value. It sits in the Geometry section of NWS Calc, a free collection of calculators that run entirely in your browser. There is no signup, no paywall and no tracking — open the page, enter your numbers, get an answer.
Frequently asked questions
- Is the Circle Calculator free to use?
- Yes. Every calculator on NWS Calc is completely free, with no signup, no usage limits and no ads.
- Does my data leave my device?
- No. The Circle Calculator runs entirely in your browser using JavaScript. Nothing you type is uploaded, logged or stored on a server.
- Can I use the Circle Calculator on my phone?
- Yes. The page is fully responsive and works in any modern mobile or desktop browser — there is nothing to install.
- What else is in Geometry?
- Area, perimeter, volume and surface area for every common shape. You can browse the full Geometry category for related calculators.