Annulus Area Calculator
Compute the area of an annulus: A = π(R² − r²).
Input Data
Outer circle radius.
Inner circle radius (r < R).
Results
84.823
Annulus area = π(R²−r²) = 84.823.
At a glance:Annulus (concentric ring) area A = π(R² − r²), R outer radius, r inner radius.
Formula
A = π(R² − r²).
How to Use
- Enter outer radius R and inner radius r.
- The tool returns annulus area A.
Case Studies
R=6, r=3 → 84.82
A = π(36−9) ≈ 84.82.
FAQ
r=0?
Degenerates to a solid circle, A = πR².
Versus circle area?
Outer circle minus inner circle.
Related Tools
References
Content reviewed by the Calculatorism editorial team. Results are for reference only; please refer to the relevant authorities for the official figures.