Circle calculator: area and circumference
Give one measurement of the circle: we work out all the others.
Result
3.141593Area
- Circumference
- 6.283185
- Radius
- 1
- Diameter
- 2
Inputs
- I know
- The radius
- Its value
- 1
How it is calculated
Area = π × r².
Result
Area
- Circumference
- 6.283185
- Radius
- 1
- Diameter
- 2
How it is calculated
- Area = π × r².
- Circumference = 2 × π × r.
- Diameter = 2 × r.
Example
A circle of radius 1 has an area of π ≈ 3.14 and a circumference of 2π ≈ 6.28.
Good to know
- Results use the same unit as your measurement (area in that unit squared).
Frequently asked questions
What is this tool used for?
Give one measurement of the circle: we work out all the others.
How is the result calculated?
Area = π × r².
What should I check before using the result?
Results use the same unit as your measurement (area in that unit squared).