Enter the rod length, bore size, suction pressure, and discharge pressure into the calculator to determine the rod load.

Rod Load Formula

The following equation is used to calculate the load on a rod.

CRL = B^2*P2 - (B^2-R^2)*P1
  • Where CRL is the compression rod load (lbf)
  • B is the bore size (in)
  • P2 is the discharge pressure (psi)
  • P1 is the suction pressure (psi)
  • R is the rod length (in)

What is a Rod Load?


A rod load is defined as the total force acting on the piston rod of a reciprocating compressor.

How to Calculate Rod Load?

Example Problem:

The following example outlines the steps and information needed to calculate Rod Load.

First, determine the rod length. In this example, the rod length is 2.5 inches.

Next, determine the bore size. This bore size is 3 inches.

Next, determine the suction pressure. The suction pressure of the compressor is measured to be 50 psi.

Next, determine the discharge pressure. The discharge pressure for this compressor is measured to be 60 psi.

Finally, calculate the rod load using the formula above:

CRL = B^2*P2 – (B^2-R^2)*P1

CRL = 3^2*60 – (3^2-2.5^2)*50

CRL = 402.5 lb-f