Enter the hole diameter, casing diameter, and casing length into the calculator to determine the annular casing capacity.

Casing Capacity Formula

The following equation is used to calculate a casing capacity between hole and casing.

AC = (Dh^2 – ODc^2) / 1029.4 * L

  • Where AC is the annular capacity/casing capacity (bbls (barrells))
  • Dh is the hole diameter (in)
  • ODc is the casing/pipe outer diameter (in)
  • L is the length (ft)

What is a casing capacity?


A casing capacity, more commonly known as annular volume, is a term used in oil drilling to describe the total volume between the casing and the hole wall.

How to calculate casing capacity?

Example Problem:

The following example outlines how to calculate a casing capacity.

First, determine the hole diameter. In this example, the hole diameter is 8 inches.

Next, determine the casing diameter. For this problem, the pipe diameter is 5 inches.

Next, determine the length. The length of the hole is 5000 feet.

Finally, calculate the casing capacity using the formula above:

AC = (Dh^2 – ODc^2) / 1029.4 * L

AC = (8^2 – 5^2) / 1029.4 * 5000

AC = 189.4 bbls