Circumference Calculator
Calculate the circumference of a circle using radius or diameter. Get exact answers in terms of π and decimal approximations.
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Frequently Asked Questions
What is the circumference of a circle?
The circumference is the distance around the circle, also known as the perimeter. It's the total length of the circle's boundary.
What is the formula for circumference?
C = 2πr (using radius) or C = πd (using diameter), where π ≈ 3.14159.
How do you find circumference from diameter?
Multiply the diameter by π: C = πd. For example, if diameter is 10, then C = 10π ≈ 31.416.
How do you find circumference from radius?
Multiply the radius by 2π: C = 2πr. For example, if radius is 5, then C = 10π ≈ 31.416.
Why is circumference important?
Circumference is used in many real-world applications, from calculating the distance traveled by a wheel to determining the amount of material needed to go around a circular object.
What's the difference between circumference and area?
Circumference measures the distance around the circle (1-dimensional), while area measures the space inside the circle (2-dimensional).
Can you measure circumference directly?
Yes, you can wrap a string or measuring tape around the circle to measure circumference directly, which is often easier than measuring the diameter for physical objects.
What are common uses of circumference?
Circumference is used in wheel and tire sizing, track lengths, circular fencing, pipe diameters, and anywhere circular measurements are needed.