🔵 Circle Calculator
Calculate all circle properties from any one value
How the Circle Calculator Works
- 1Enter any single known value: radius, diameter, circumference, or area.
- 2The calculator derives the radius from whichever value you provide.
- 3From the radius, all other properties are computed.
- 4Diameter = 2r, Circumference = 2πr, Area = πr².
- 5Every formula step is shown for learning.
About Circle Calculator
Complete circle calculator. Enter any one value — radius, diameter, circumference, or area — and instantly get all other circle measurements with formulas.
Frequently Asked Questions
Can I enter the area and get the radius?
Yes. If you enter the area A, the calculator finds the radius as r = √(A/π), then computes diameter and circumference.
What is the relationship between circumference and diameter?
Circumference = π × diameter. This is the definition of π — the ratio of a circle's circumference to its diameter, approximately 3.14159.
Are the formulas exact?
The formulas are exact. The numerical results are approximate because π is irrational and cannot be expressed as a finite decimal.