A system and method for calibrating an IV pump infusion system tube comprises a fluid source, an infusion system comprising, an IV pump, a drive unit, a chamber with known constant volume, a control unit, and IV tubing with a known inner diameter tolerance, and a switch and magnetic floating object. The system administers medicinal fluid, calculates the flow rate of the medicinal fluid in the chamber by measuring the time the switch is activated as medicinal fluid rises in the chamber, compares the calculated flow rate with a set flow rate of the IV pump input in the control unit prior to infusion, and adjusts the IV pump and flow rate based on the compared deviations for more accurate delivery to a patient. This configuration may provide a more precise delivery rate of medicinal fluid, preventing harm to the patient and waste of medicine.