Convert pump RPM to mL/min flow from the displacement per revolution and volumetric efficiency, or solve for the RPM or displacement a flow needs.

Positive-displacement estimate. For geometric displacement, 100% efficiency gives theoretical flow. Use data for the operating condition. US gallons are used.

Use 100% when the volume per revolution is already calibrated to actual delivery; do not apply delivery losses twice.

RPM to mL/min Formula

For geometric displacement, the following formula estimates delivered flow using volumetric efficiency. Set ฮทv = 1 for theoretical flow. When using calibrated actual delivery per revolution, use a factor of 1 to avoid applying the same delivery loss twice.

FR = RPM ร— DV ร— etaแตฅ / 1000

Variables:

  • FR is the flow rate (mL/min)
  • RPM is the revolutions per minute
  • DV is displacement in ฮผL/rev; ฮทv is volumetric efficiency as a fraction (percentage รท 100).

With displacement in ฮผL/rev, multiply RPM by displacement and the efficiency fraction, then divide by 1000 to convert ฮผL to mL. With displacement in mL/rev, omit the division by 1000. One inยณ is exactly 16.387064 mL; one US gallon is exactly 3785.411784 mL.

RPM to mL/min Conversion Table (Dispenser Volume = 1 ฮผL/rev)
RPM Flow Rate (mL/min)
10.001
50.005
100.010
150.015
200.020
300.030
450.045
600.060
750.075
900.090
1200.120
1500.150
1800.180
2400.240
3000.300
3600.360
4800.480
6000.600
8000.800
10001.000
* Rounded to 3 decimals. Assumes dispenser volume: 1 ฮผL per revolution. Formula: mL/min = RPM ร— 0.001 at 100% volumetric efficiency. 1 L/min = 1000 mL/min. This is a theoretical/reference table, not a pump calibration.

What is RPM to mL/min Conversion?

For a positive-displacement pump, delivery is proportional to RPM when effective displacement per revolution and volumetric efficiency remain constant. Peristaltic delivery also depends on tubing, fluid, pressure and wear. Calibrate under the intended conditions or use manufacturer performance data; the simple equation does not predict centrifugal-pump flow, pressure or power.

How to Calculate Flow Rate from RPM?

The following steps outline how to calculate the flow rate from RPM.

  1. First, determine the RPM (revolutions per minute).
  2. Next, determine the dispenser volume (DV) in ฮผL/rev.
  3. Use FR = RPM ร— DV ร— ฮทv / 1000 for DV in ฮผL/rev; enter ฮทv as a fraction. Use ฮทv = 1 for theoretical or already-calibrated delivery per revolution.
  4. Finally, calculate the flow rate (FR) in mL/min.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

RPM (revolutions per minute) = 120 RPM

Dispenser Volume (DV) = 50 ฮผL/rev. At ฮทv = 1, flow = 120 ร— 50 / 1000 = 6 mL/min. If this is geometric displacement and volumetric efficiency is 90%, delivered flow is 5.4 mL/min.