Circumference of a Circle Calculator
⬛ Area & perimeter (2D). Use the Circumference of a circle formula to find circumference, radius: pick the value you want, type the others, and the answer updates as you go.
Circumference31.416 cm
Pick the ○ next to the value you want to find, fill in the others, and it solves as you type.
What each letter means
| Quantity | Unit |
|---|---|
| Circumference | cm |
| Radius | cm |
Worked example
Find the circumference when Radius = 5 cm.
Using C = 2π r = π d: Circumference = 31.416 cm.
Frequently asked questions
What is the formula for Circumference of a circle?
C = 2π r = π d.
What do the letters stand for, and what units are used?
Circumference in cm, Radius in cm.
How do you calculate circumference?
Put the values into C = 2π r = π d. For example, with Radius = 5 cm, circumference = 31.416 cm.
Can I solve for a different value?
Yes. In the calculator above, pick the circle next to any value (circumference, radius) and fill in the others: it rearranges the formula for you.
