Annulus Area Calculator
Find the area of an annulus or ring shape from inner and outer radius instantly with this free geometry calculator in your browser.
Enter Values
Shape
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter the outer and inner radius.
- Press Calculate.
How it works
Area of a ring = π × (outer radius² − inner radius²).
Worked example
outer 2 m, inner 1 m. ≈ 9.42 m².
Common mistakes
- Subtracting the radii then squaring — square each radius first, then subtract.
- Mixing inner and outer diameters with radii; halve diameters before using.
Frequently asked questions
How do I find the area of an annulus?
Subtract the inner circle from the outer: Area = π × (R² − r²), where R is the outer and r the inner radius.
What is an annulus?
The ring-shaped region between two concentric circles — like a washer or a circular path between two boundaries.
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Cite this tool
Zerdly. (2026). Annulus Area Calculator. Retrieved from https://www.zerdly.com/tools/annulus-area-calculator/
Tip: Enter any known values to calculate the remaining results.
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