Home/Math/Circle
Circle Calculator
Diameter:10.0
Circumference:31.42
Area:78.54
Home/Math/Circle
Add this free circle calculator to your website or blog.
Always double-check if you are given the radius or the diameter. Mixing them up is the #1 mistake. Remember: Diameter = 2 × Radius.
If your radius is in cm, your area will be in cm² (square centimeters). Don't forget the "square" part for area!
For most school problems, 3.14 is enough. For higher precision, use the π button on your calculator (or 3.14159...).
In the area formula A = πr², only the radius (r) is squared, not π. It's π × (r × r), not (π × r)².
Circumference is 2πr. Area is πr². They look similar, but one measures length (distance around) and the other measures space inside.
Don't round your intermediate numbers. Keep the full value of π in your calculator until the very last step to get the most accurate answer.