How to use this calculator
Enter the radius, which is the distance from the center to the edge. If you measured a diameter, divide it by two first.
Formula
A = πr²; P = 2πr
Worked example
A circle with radius 3 m has area π × 3² ≈ 28.2743 m² and circumference 2π × 3 ≈ 18.8496 m.
Assumptions and limits
The model is a perfect flat circle. Rounded results use the numerical value of π; irregular outlines require another measurement method.
Frequently asked questions
What if I know the diameter?
Divide the diameter by two to get the radius. A 10 m diameter means a 5 m radius.
What units should I use?
Choose your input unit, then enter every dimension in that unit. The result unit can be changed independently.
Does this include waste or material costs?
No. This is geometric area only. Add openings, overlap, cutting waste, prices and installation requirements separately.
Calculated locally; rounded only for display.