Circle Area Calculator

Q: "How do I find the area of a circle?"

"A = πr² where r is the radius. Or A = π(d/2)² using diameter d."

Q: "What is the formula for circle area?"

"Area = π × radius². π ≈ 3.14159."

Q: "Can I enter radius or diameter?"

"Yes. Choose \"Radius\" or \"Diameter\" and enter the value. The calculator gives the area."

Q: "What units does the result use?"

"If you enter radius in meters, area is in square meters (m²). Same for feet (ft²), etc."

Q: "How is area related to circumference?"

"Area = C²/(4π) where C is circumference. Or from radius, A = πr² and C = 2πr."

Calculate circle area from radius or diameter. Example: radius 5 → area 78.54. Formula A = πr². Copy result.

The area of a circle is π times the square of the radius: A = πr². If you have the diameter d, then A = π(d/2)². Enter the radius or diameter and choose which one you entered. The result is in square units of the same length (e.g. m² if input was in m). Copy the result or Copy with labels.

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Examples

radius 5 → A ≈ 78.54
diameter 10 → A ≈ 78.54
radius 1 → A ≈ 3.14

FAQ

How do I find the area of a circle?

A = πr² where r is the radius. Or A = π(d/2)² using diameter d.

What is the formula for circle area?

Area = π × radius². π ≈ 3.14159.

Can I enter radius or diameter?

Yes. Choose "Radius" or "Diameter" and enter the value. The calculator gives the area.

What units does the result use?

If you enter radius in meters, area is in square meters (m²). Same for feet (ft²), etc.

How is area related to circumference?

Area = C²/(4π) where C is circumference. Or from radius, A = πr² and C = 2πr.