Annulus Calculator

Calculate the area, circumference, and thickness of an annulus using the outer and inner radius.

Annulus Area Formula

A = π(R² − r²)

R = Outer Radius    |    r = Inner Radius

Outer Radius (R)

Inner Radius (r)

Unit Millimeters (mm) Centimeters (cm) Meters (m) Inches (in) Feet (ft)

Decimal Places 0 1 2 3 4 5 6

Results

Annulus Area

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Outer Circumference

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Inner Circumference

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Annulus Thickness

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Note: The outer radius must be greater than the inner radius. The annulus is the region between two concentric circles.

``` ### Features * Outer radius and inner radius inputs * Annulus area calculation: **A = π(R² − r²)** * Outer circumference * Inner circumference * Annulus thickness * mm, cm, m, inches, and feet units * Adjustable decimal precision * Input validation * Detailed calculation steps * Responsive mobile-friendly design * Reset button * No external libraries required