Circle Calculator

Your details

Pick whichever measurement you already have; the rest are solved from it.
Enter the measurement you selected above. The unit applies to all linear results; area is in that unit squared.
Unlock sector area and arc length by entering a central angle.
Area
78.5398 (= 25π) cm²

pi times radius squared

Circumference31.4159 (= 10π) cm
Diameter10 cm
Radius5 cm

From Radius = 5 cm: 78.5398 area, 31.4159 circumference.

  • Area grows with the square of the radius: doubling the radius quadruples the area.
  • Circumference grows linearly: it is always pi times the diameter, regardless of size.
  • All four circle properties are exactly determined by any single one of them.

Next stepIf you know the diameter instead, switch "I know the" to Diameter above.

 = Powered by OnlyCalculators