Donut (Annulus) Area Calculator
The Donut Area Calculator finds the area of an annulus (a ring or donut shape) from its outer and inner radii, plus both circumferences. Enter the radii.
Formula
Annulus Area = π(R² − r²)
- The ring area is the outer circle area minus the inner circle area.
- The ring width is simply R − r.
Outer 10, inner 6
Inputs
- Outer Radius: 10
- Inner Radius: 6
π(100 − 36) = 64π ≈ 201.06.
Frequently asked questions
What is an annulus?
The ring-shaped region between two concentric circles. Its area is π times the difference of the squared radii.