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Annulus (Ring) Area Calculator

Area between two concentric circles: π(R² − r²).

Compute the area of an annulus (the region between two concentric circles) from the outer and inner radii: A = π · (R² − r²). Reports outer-circle area, inner-circle area, and ring width.

Daniel Oh By Daniel Oh
Published Last reviewed 1 min read

Inputs

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

A = π · (R² − r²)

In depth

Compute the area of an annulus (the region between two concentric circles) from the outer and inner radii: A = π · (R² − r²). Reports outer-circle area, inner-circle area, and ring width.