Calculate Areas & Properties of Annulus Rings

Ring shapes are essentially formed by one circle within another. To caculate the area of an annulus ring, take the difference between the two circle areas.

With this calculator tool, you can calculate the Outer Radius (R), Inner Radius (r), Witdth or Thickness (w), Area (A), Inner Circumference (ic) or Outer Circumference (oc), and even the Central Area (ca).

Area = π x (R2 - r2)

Outer Radius (R)
Inner Radius (r)
Width (w)
Area (A)
Outer (oc)
Inner (ic)
Centre Area (ca)

*All radii, widths, and circumferences are in units length ( All areas will be in units squared (e.g. cm2).