Our OneHydraulics Pump Sizing Calculator makes it easy to determine the right pump specifications for your system. Just enter any three variables—output pressure, flow rate, pump efficiency, horsepower, or motor speed—and it will calculate the missing value. With support for multiple units, this tool helps you quickly size your pump for optimal performance, ensuring efficiency and reliability in your hydraulic setup.


Enter any three values to calculate the fourth. You can change units as needed.

Terminology Defined

Output Pressure (P)


Flow Rate (Q)



Pump Efficiency



Horsepower (HP)



Motor Speed (n)



Torque (T)



Displacement (d)



Force per unit area generated by a pump or motor to move fluid through the system, typically measured in PSI or bar


Flow rate is the volume of fluid a pump or motor moves per unit of time, typically measured in gallons per minute (GPM) or liters per minute (LPM)


Ratio of the pump’s hydraulic power output to its mechanical power input, expressed as a percentage, indicating how effectively the pump converts energy into fluid movement


Measure of the pump’s mechanical power output, calculated based on flow rate, pressure, and efficiency to determine the energy required to drive the pump.


Rotational speed of a hydraulic or electric motor driving a pump, typically measured in revolutions per minute (RPM), which directly impacts flow rate and system performance


Rotational force generated by a hydraulic motor or required to drive a pump, typically measured in pound-feet (lb-ft) or Newton-meters (Nm), and is directly related to pressure and displacement.


Volume of fluid a pump or motor moves per revolution, typically measured in cubic inches per revolution (in³/rev) or milliliters per revolution (mL/rev), directly affecting flow rate and torque output.



Disclaimer: The calculators provided on this site are for reference purposes only. OneHydraulics makes no guarantees regarding the accuracy, completeness, or applicability of the data generated. Users are responsible for verifying the results and ensuring the safe and satisfactory operation of any equipment designed based on this information. OneHydraulics assumes no liability for errors, omissions, or any outcomes related to the use of these tools. Always consult a qualified professional for critical system designs or safety-related applications.





Still need help? Give us a call at 281.941.2310 or email us at sales@onehydraulics.com for technical support.