What is the area of a circle?
The area of a circle is the space enclosed within its boundary. It is measured in square units (e.g., cm², m²). The area depends on the length of the radius or diameter.
How to calculate the area of a circle?
You can calculate the area of a circle in two ways:
- From radius: A = π × r², where r is the radius
- From diameter: A = π × (d/2)², where d is the diameter
Enter the radius or diameter and the calculator will automatically compute the area, circumference and other values.
What is the circle area formula?
The standard formula is A = π × r². Here π (pi) is a mathematical constant approximately equal to 3.14159. The radius r is the distance from the center of the circle to any point on its edge. If you know the diameter d, the radius equals d/2.
Circle area calculation examples
- Radius 5 cm: A = π × 5² = π × 25 ≈ 78.54 cm²
- Diameter 10 m: r = 10/2 = 5 m, A = π × 25 ≈ 78.54 m²
- Radius 1 m: A = π × 1² ≈ 3.14 m²
When to use a circle area calculator?
A circle area calculator is useful in many everyday situations:
- Calculating the area of a round table, pool or trampoline
- Determining pipe cross-section area
- Computing circular garden or lawn areas
- Solving math homework problems
What is the difference between radius and diameter?
The radius (r) is the distance from the center of a circle to its edge. The diameter (d) is the distance across the entire circle through the center. The diameter is always twice the radius: d = 2r.