Circle Geometry Calculator & Visualizer

What is Pi?

π (Pi)

The Circle Constant

The ratio of any circle's circumference to its diameter. Regardless of size, this ratio is always π ≈ 3.14159...

If diameter = 1, then the perimeter = π

An irrational number — its decimals never end or repeat. Ancient mathematicians discovered this constant appears universally in all circles, nature, and physics.

Standard Dimensions

Radius (r)

Diameter (d)

Circumference (C)

Area (A)

m²

Formulas appear here...

Sector & Arc

Advanced

Sector Angle (θ)

deg

Arc Length (s)

- m

Chord (L)

- m

Sector Area

- m²