Circle Calculator
Formulas:
Diameter (d) = 2 × radius
Circumference (C) = 2 × π × r = π × d
Area (A) = π × r²
Enter any ONE value and calculate all the others!
About This Tool
Calculate any circle property when you know just one value. Useful for:
- Pizza sizing (area from diameter)
- Wheel measurements
- Round table dimensions
- Garden bed circles
- Pool or tank capacity