Annulus Area Calculator
Compute the area of an annulus (ring) from the outer and inner radii.
Inputs
units
units
Annulus Area
201.0619sq units
Step by step
Apply annulus formula
A = π × (10² − 6²) = π × 64
= 201.0619
How it works
An annulus is the region between two concentric circles. Its area is the difference of the two circle areas: π(R² − r²).
Formula
Annulus Area
A = π(R² − r²)
- R
- Outer radius
- r
- Inner radius
Frequently Asked Questions
What if the inner radius is zero?
Then the annulus becomes a full circle with area πR².
Can I use diameter instead of radius?
Yes — divide each diameter by 2 to get the corresponding radius, then apply the formula.