The flow rate of a working peristatic pump depends on several parameters including the rotor speed, the tubing inner diameter and wall thickness, as well as the backpressure of the suction side. For a specific tubing with a constant length, the flow rate is proportional to the pump rotor speed. Therefore, the flow rate at a given rotor speed can be calibrated by measuring the total amount of liquid that is delivered in a specific time duration.

To obtain the accurate amount of liquid delivered, the tubing should be completely filled with the liquid before starting the dispensing of liquid.

For example, suppose the pumping time duration is t (min), and the delivered amount of liquid is m in gram (or volume V in milliliter), then the flow rate can be expressed as the following formula:

Mass Flow Rate = m/t (g/min)

Or Volume Flow Rate = V/t (mL/min)

To perform mass flow rate calibration, the delivered liquid in time t can be dispensed in a beaker and then the net liquid mass can be weighed on a scale or a lab balance.

For volume flow rate, the liquid can be dispensed to volumetric cylinder to measure the volume after the time of pumping.

Note that the flow rate may need to be calibrated once in a while (e.g. 3 days to 1 week) because the tubing relaxation may change due to repeated compression.