Enter the motor displacement (in^3/rev) and the motor RPM into the calculator to determine the hydraulic motor flow.

Hydraulic Motor Formula

The following formula is used to calculate the flow required to fuel a hydraulic motor. 

HF = D * RPM /231
  • Where HF is the hydraulic motor flow required (GPM)
  • D is the motor displacement (in^3 / rev)
  • RPM is the rotations per minute of the motor

To calculate the hydraulic motor flow, multiply the motor displacement by the RPM, then divide by 231.

Similarly, the RPM can also be calculated by re-arranging the equation above to the following:

RPM = HF / D * 231

Where RPM is the motor speed in rotation per minute.

What is a hydraulic motor?

A hydraulic motor is a type of motor that runs on hydraulic fluid flow in order to produce rotation and torque within the motor.

How to calculate hydraulic motor flow?

The following example outlines the steps needed to calculate the volumetric flow of a hydraulic motor.

First, determine the motor displacement. This should be in units of cubic inches per revolution. For this example, the motor displacement is 4 in^3/rev.

Next, determine the motor RPM. In this case, the motor has a designed RPM of 2000.

Finally, calculate the required flow in order to run the motor at the speed above.

HF = D * RPM /231

HF = 4 * 2000 /231

HF = 34.63 GPM