A circle calculator computes all the key measurements of a circle, area, circumference (perimeter), and diameter, from a single input: the radius.
About this calculator
A circle calculator computes all the key measurements of a circle, area, circumference (perimeter), and diameter, from a single input: the radius. These calculations are needed in many practical contexts from circular rooms and pools to pipes, wheels, and circular foundations.
Circle formulas: Area = π×r². Circumference = 2×π×r. Diameter = 2×r. Where r is the radius and π ≈ 3.14159.
Common uses
- Calculate the area of a circular garden or pool
- Find the circumference of a wheel or circular track
- Determine pipe cross-sectional area for flow calculations
- Calculate material needed for a circular project
Frequently asked questions
What is the relationship between radius, diameter, and circumference?
Diameter = 2 × radius. Circumference = π × diameter = 2 × π × radius. For a circle with radius 5m: diameter = 10m, circumference ≈ 31.42m, area ≈ 78.54m².