Circumference of a Circle Calculator
Calculates the circumference of a circle from the measurements you enter. Use any unit, as long as all inputs use the same one.
Result
- Circumference
- 31.4159
How to use the circumference of a circle calculator
- Enter the radius.
- The results update as you type, or press Calculate.
- Read the circumference first, then the supporting figures below it.
Formula
2πr
Worked example
For example, with these inputs:
- Radius: 5
the calculator returns:
- Circumference: 31.4159
Background
Each formula has assumptions built in. Area formulas assume flat shapes, volume formulas assume regular solids and statistical measures assume the data you enter is the data you want to describe. Knowing the assumptions helps you pick the right tool.
Calculators are best used to check working rather than replace it, especially for exams where method marks count. Work the problem by hand first, then confirm with the calculator.
Frequently asked questions
How does the circumference of a circle calculator work?
It applies this formula: 2πr
Can I use any units?
Yes, as long as every input uses the same unit. The answer will be in that unit (squared for areas, cubed for volumes).