Annulus (Ring) Area Calculator
Area of a ring from the outer and inner radius, with the wall thickness.
Results
Area
5026.548
mm²
Thickness
20.000
mm
Area
50.2655
cm²
Length
251.327
mm
What this tool does
The annulus is the cross-section of every tube, washer and pipe, and it is the area that carries the load when you calculate stress in a hollow shaft. Subtracting the inner circle from the outer one is all there is to it.
Formula
A = π × (R² − r²)
Variables
| Symbol | Meaning | Unit |
|---|---|---|
ro | Outer radius | mm |
ri | Inner radius | mm |
A | Area | mm² |
W | Thickness | mm |
AC | Area | cm² |
ML | Length | mm |
Worked example
- Outer radius50 mm
- Inner radius30 mm
- Area5026.548 mm²
- Thickness20.000 mm
- Area50.2655 cm²
- Length251.327 mm
Limitations
- Mixing units is the most common source of error. Convert every input to the units shown next to each field before calculating.