Circumference Calculator

One circle value in, four circle values out. Given the radius, diameter, circumference or area, this tool derives the rest using C = 2πr and A = πr².

🔬 Full derivation

All four properties from one input.

🔢 π precision

Uses JavaScript’s high-precision PI.

📊 Any starting point

Radius, diameter, circumference or area.

✓ Formulae shown

See the exact relationship used.

More geometry tools

Shape math made simple.

Area → Pythagorean Golden Ratio

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