Circle Area Calculator
Calculate circle area, circumference, and diameter from radius.
Enter Radius
Area: 78.54 square units
Circumference: 31.42 units
Diameter: 10 units
Circumference: 31.42 units
Diameter: 10 units
Calculations:
Area: A = πr² = π(5)² = 25π = 78.54
Circumference: C = 2πr = 2π(5) = 10π = 31.42
Diameter: d = 2r = 2(5) = 10
Circle Formulas
Area: A = πr²
Circumference: C = 2πr = πd
Diameter: d = 2r
where: - r = radius - d = diameter - π ≈ 3.14159
How to Calculate Circle Area
- Measure the radius (distance from center to edge)
- Square the radius (multiply it by itself)
- Multiply by π (approximately 3.14159)
Understanding the Formulas
- Area measures the space inside the circle
- Circumference measures the distance around the circle
- Diameter is twice the radius
Real-World Applications
Circle calculations are used in: - Engineering and design - Architecture - Manufacturing - Sports (track and field) - Astronomy
Common Questions
What is the formula for circle area?
The circle area formula is A = πr², where r is the radius. Pi (π) is approximately 3.14159.
How do you find circumference of a circle?
The circumference formula is C = 2πr or C = πd, where r is radius and d is diameter.