Area of a Circle Calculator
Calculate the area of a circle using radius or diameter. Get instant results with step-by-step solutions and visual formulas.
Input Method
cm
Formula
A = π × r²
Where:
- A =Area of the circle
- π =Pi (≈ 3.14159)
- r =Radius of the circle
Circle Diagram
Red line: Radius (r)
Green line: Diameter (d = 2r)
Shaded area: Circle area (A = πr²)
Common Circle Areas
RadiusArea
1 unitπ ≈ 3.14 units²
2 units4π ≈ 12.57 units²
3 units9π ≈ 28.27 units²
5 units25π ≈ 78.54 units²
10 units100π ≈ 314.16 units²
Understanding Circle Area
What is Circle Area?
The area of a circle is the amount of space enclosed within the circle's boundary. It's measured in square units and represents the total surface inside the circle.
Key Formulas
- Area from radius: A = πr²
- Area from diameter: A = π(d/2)² = πd²/4
- Radius from area: r = √(A/π)
- Diameter from area: d = 2√(A/π)
Real-World Applications
- • Architecture: Calculating floor space for circular rooms
- • Landscaping: Determining area for circular gardens or lawns
- • Engineering: Computing cross-sectional areas of pipes
- • Manufacturing: Material requirements for circular components
- • Sports: Field dimensions for circular or curved areas
Tips for Accuracy
- • Use more decimal places of π for precise calculations
- • Double-check whether you have radius or diameter
- • Ensure consistent units throughout your calculation
- • Remember that area is always in square units
Frequently Asked Questions - Area of a Circle Calculator
The formula for the area of a circle is A = πr², where A is the area, π (pi) ≈ 3.14159, and r is the radius of the circle.
Tips
- Enter the dimensions in the same unit for consistency.
- Results update automatically as you type.
- Use the unit selector to convert between different measurement systems.