Area of Shaded Region Circle Calculator

The shaded region is the ring-shaped area (annulus) between two concentric circles that share the same center point. It is the donut-shaped area you get when you subtract a smaller circle from a larger one.

No. The outer radius must be strictly larger than the inner radius to create a ring with area. If they are equal, the shaded area is zero because both circles overlap completely.

They calculate the same thing. "Area of shaded region" is how this problem is commonly phrased in school textbooks and exams, while "annulus area" is the formal mathematical term. Both use the formula pi x (R^2 - r^2).

This calculator requires radii. If you have diameters, divide each by 2 before entering. For example, outer diameter 20 becomes outer radius 10, and inner diameter 12 becomes inner radius 6.

Circular running tracks (the track surface between the inner and outer edges), washer hardware (the flat ring around the hole), circular garden beds around fountains, and pipe cross-sections (the material between inner bore and outer wall).

Yes, embedding the Area of Shaded Region Circle Calculator is free. Hit the "Embed" button on this page, adjust the width, height, and theme, then grab the iframe code. It works on WordPress, Wix, Squarespace, Shopify, and plain HTML pages. No registration needed. Full instructions at calculory.com/services/embed-calculators.