Hollow Circle (Annulus)  Geometric Properties
Geometric Property Calculator  



The above hollow circle (annulus) property calculator is based on the provided equations and does not account for all mathematical limitations. The calculator has been provided with educational purposes in mind and should be used accordingly. Unit conversion
Need an spreadsheet for designing the above shape, click here!
Notation and Units
Metric and Imperial Units
The above formulas may be used with both imperial and metric units. As with all calculations care must be taken to keep consistent units throughout. Examples of units which are typically adopted are outlined below:
Notation
 A = Geometric Area, in^{2} or mm^{2}
 C = Distance to Centroid, in or mm
 I = Second moment of area, in^{4} or mm^{4}
 J_{i} = Polar Moment of Inertia, in^{4} or mm^{4}
 J = Torsional Constant, in^{4} or mm^{4}
 K = Radius of Gyration, in or mm
 P = Perimeter of shape, in or mm
 S = Plastic Section Modulus, in^{3} or mm^{3}
 Z = Elastic Section Modulus, in^{3} or mm^{3}
Online Hollow Circle (Annulus) Property Calculator
Using the structural engineering calculator located at the top of the page (simply click on the the "show/hide calculator" button) the following properties can be calculated:
 Calculate the Area of a Hollow Circle or Annulus
 Calculate the Perimeter of a Hollow Circle or Annulus
 Calculate the Centroid of a Hollow Circle or Annulus
 Calculate the Second Moment of Area (or moment of inertia) of a Hollow Circle or Annulus
 Calculate the Polar Moment of Inertia of a Hollow Circle or Annulus
 Calculate the Radius of Gyration of a Hollow Circle or Annulus
 Calculate the Elastic Section Modulus of a Hollow Circle or Annulus
 Calculate the Plastic Section Modulus of a Hollow Circle or Annulus