Circumference Calculator
Calculate circle circumference from radius, diameter, or area.
Table of Contents
How to Use
- Select your input method (radius, diameter, or area).
- Enter the known measurement value.
- Click Calculate to find the circle circumference.
- View the circumference along with all other circle measurements.
What Is Circumference?
The circumference of a circle is the distance around its edge. It is the perimeter of the circle and is calculated using the formula C = 2πr or C = πd, where r is the radius, d is the diameter, and π (pi) is approximately 3.14159.
Circumference is a fundamental measurement in geometry and is used in countless real-world applications from wheel design to planetary orbits.
Circle Formulas
- Circumference: C = 2πr = πd
- Area: A = πr²
- Diameter: d = 2r
- Radius: r = d/2 = C/(2π)
Real-World Applications
Circumference calculations are essential in many fields: designing wheels and gears, measuring track distances, calculating belt lengths, determining fence requirements for circular areas, and computing planetary orbits in astronomy.
Frequently Asked Questions
- What is the formula for circumference?
- The formula for the circumference of a circle is C = 2πr or C = πd, where C is the circumference, π is approximately 3.14159, r is the radius, and d is the diameter.
- Can I calculate circumference from area?
- Yes! This calculator can determine circumference from area. It first calculates the radius using r = √(A/π), then uses C = 2πr to find the circumference.
- What's the difference between circumference and perimeter?
- Circumference is specifically the perimeter of a circle. For circles, the terms are interchangeable, but 'perimeter' is used for all shapes while 'circumference' is reserved for circles.