Circle Formula Calculator
Calculate radius, diameter, circumference, and area of a circle with complete formulas
Calculate Circle Properties
Select which measurement you have
Enter a positive value
Circle Properties
Formulas Used
Example Calculation
Pizza Circle Example
Problem: A pizza has a radius of 6 inches. Find its diameter, circumference, and area.
Given: Radius (r) = 6 inches
Solution
Diameter: d = 2r = 2 × 6 = 12 inches
Circumference: c = 2πr = 2 × π × 6 = 37.699 inches
Area: A = πr² = π × 6² = π × 36 = 113.097 square inches
Circle Properties
Radius
Distance from center to edge
Half of the diameter
Diameter
Distance across the circle
Twice the radius
Circumference
Distance around the circle
Perimeter of the circle
Area
Space inside the circle
Measured in square units
Circle Formulas
Understanding Circle Formulas
What is a Circle?
A circle is a perfectly round shape where every point on the edge is exactly the same distance from the center. This distance is called the radius, and it's fundamental to all circle calculations.
Key Components
- •Center: The exact middle point of the circle
- •Radius: Distance from center to any point on the circle
- •Diameter: Distance across the circle through the center
- •Circumference: Distance around the outside of the circle
Formula Applications
Real-World Uses
- • Calculating pizza area for pricing
- • Designing circular gardens or pools
- • Engineering wheel and tire specifications
- • Architecture and construction planning
- • Sports field design (running tracks, etc.)
Why π (Pi)?
Pi (π) is the ratio of a circle's circumference to its diameter. This ratio is the same for all circles, approximately 3.14159. It's an irrational number, meaning its decimal representation never ends or repeats.