Calculate a circle’s area using radius or diameter. If your project involves straight edges instead, try our Square Area Calculator. Results include conversions to square meters, square feet, and acres.
Area represents the total surface inside a shape’s boundary. This calculator applies the standard geometry formula for this shape and multiplies the required dimensions together to produce the total area.
All calculations are performed instantly in your selected unit. Results are also converted automatically to square meters, square feet, and acres where relevant, making it easier to compare measurements across different projects.
Either one works. If you enter diameter, radius is d ÷ 2.
π (pi) is approximately 3.14159.
This calculator prioritizes radius if it’s entered; otherwise it uses diameter.