Geometry & Measurement Calculators
Annulus Area Calculator
Find the area of a ring (annulus) from its two radii.
Loading tool…
What is Annulus Area?
An annulus is the ring between two concentric circles. Its area is the outer circle's area minus the inner circle's.
How it works
We subtract the square of the inner radius from the square of the outer radius and multiply by π, rejecting an inner radius that is not smaller than the outer.
- Enter your input. Type or paste your input into the field above — the tool responds instantly.
- Review the result. Output updates live as you type. Everything runs entirely in your browser.
- Copy or download. Use the Copy button to grab the result, or Download to save it as a file.
Examples
Realistic sample
Type or paste any realistic input — the tool computes the result locally and instantly.
Common mistakes
Expecting a server round-trip
Nothing is uploaded — every tool in this category runs entirely in your browser.