How to use the annulus area calculator
Find the area and width of a flat ring between two concentric circles. Enter outer radius, inner radius in the fields above; the area of ring, ring width are computed instantly and plotted on the chart so you can see how the answer changes.
Common searches this calculator answers include “ring area”, “washer area”, “annulus area between two circles”, “calculate annulus area”, “find area of ring”.
Formula
Variables
- R — Outer radius (cm)
- r — Inner radius (cm)
Worked example
With outer radius = 10 cm, inner radius = 6 cm, the calculator gives area of ring ≈ 201.0619 cm²; ring width ≈ 4 cm.
Frequently asked questions
What is the annulus area calculator used for?
Find the area and width of a flat ring between two concentric circles. It helps with questions such as “ring area”, “washer area”, “annulus area between two circles”.
What is the formula for the annulus area calculation?
Area of ring (cm²) = π × (R × R-r × r). Ring width (cm) = R-r. Here R is outer radius (cm), r is inner radius (cm).
What inputs do I need for the annulus (ring) area calculator?
You need outer radius in cm, inner radius in cm. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use the annulus area calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the annulus area result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.