Annulus area subtracts the smaller inner circle from the larger outer circle. The remaining region is a ring, so the formula uses the difference of squared radii multiplied by π.
⚠Use nonnegative radii, with the outer radius greater than or equal to the inner radius.
How Annulus Area Works
An annulus is the region between two circles sharing the same center. Its area is found by subtracting the hole from the full outside circle.
Outer Circle
The larger circle gives the total area.
Inner Circle
The smaller circle is removed.
Same Center
The circles are concentric.
Ring Shape
The result is the remaining band.
💡 Example: For R=5 and r=3, A=π(25-9)=50.265.
Applications of Annulus Area
WashersRingsPipesCircular Paths
Frequently Asked Questions
What is an annulus area calculator?▼
It calculates the area between two concentric circles.
What is the annulus area formula?▼
The formula is A=π(R²-r²), where R is outer radius and r is inner radius.
How do I use this calculator?▼
Enter outer radius and inner radius, then click Calculate.
Can inner radius be larger than outer radius?▼
No. The inner radius must be less than or equal to the outer radius.
Where is annulus area used?▼
It is used for washers, rings, pipes, circular paths, and mechanical design.
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