Enter the pump RPM and the pump displacement (in^3/revolution) into the RPM to Flow Rate Calculator. The calculator will evaluate the RPM to Flow Rate. 

RPM to Flow Rate Calculator

RPM to Flow
Flow to RPM
Advanced Pump
Use a known flow at a known RPM to estimate flow at a different RPM.

RPM to Flow Rate Formula

The following two example problems outline the steps and information needed to calculate the RPM to Flow Rate.

FR = RPM * D / 231
  • Where FR is the RPM to Flow Rate (GPM)
  • RPM is the pump RPM 
  • D is the pump displacement (in^3/revolution) 

To calculate a flow rate from RPM, multiply the RPM by the displacement, then divide by 231.

RPM to Flow Rate Conversion Table (Displacement = 1.00 in³/rev, Efficiency = 1.00)
RPM Flow Rate (GPM) Flow Rate (L/min)
1000.4331.639
2501.0824.097
3001.2994.916
5002.1658.194
6002.5979.832
7503.24712.290
9003.89614.748
1,0004.32916.387
1,2005.19519.665
1,5006.49424.581
1,7507.57628.677
1,8007.79229.497
2,0008.65832.774
2,2009.52436.052
2,40010.39039.329
2,50010.82340.968
3,00012.98749.161
3,20013.85352.439
3,45014.93556.535
3,60015.58458.994
* Rounded to 3 decimals. Assumes Displacement = 1.00 in³/rev and Efficiency = 1.00. Formula: Q(GPM) = RPM × Displacement × Efficiency ÷ 231. Conversion: 1 GPM = 3.78541 L/min.

How to Calculate RPM to Flow Rate?

The following example problems outline how to calculate RPM to Flow Rate.

Example Problem #1:

  1. First, determine the pump RPM.
    • The pump RPM is given as: 400.
  2. Next, determine the pump displacement (in^3/revolution).
    • The pump displacement (in^3/revolution) is provided as: 2.5.
  3. Finally, calculate the RPM to Flow Rate using the equation above: 

FR = RPM * D / 231

The values provided above are inserted into the equation below and computed.

FR = 400 * 2.5 / 231 = 4.239 (GPM)


Example Problem #2: 

For this problem, the variables required are provided below:

pump RPM = 600

pump displacement (in^3/revolution) = 3

Test your knowledge using the equation and check your answer with the calculator..

FR = RPM * D / 231 = ?