A peristaltic pump is disclosed that includes a plunger, a spring, an actuator, a position sensor, and a processor. The plunger actuates toward and away from a tube. The spring biases the plunger toward the tube. The actuator actuates the plunger away from the tube and mechanically engages and disengages from the plunger. The position sensor senses a position of the plunger. The processor receives the sensed position of the plunger and estimates fluid flow within the tube using a first position of the plunger when the actuator is engaged with the plunger and a second position of the plunger when the actuator is disengaged from the plunger.