Tourniquet use always carries potential risks, which can range from mild transient functional impairments of thigh pain, skin blisters to severe permanent dysfunction of limb paralysis, nerve injuries or compartment syndrome. The ideal method for minimizing intraoperative tourniquet pressure (TP) for reducing postoperative complications remains controversial. In this prospective, randomized and controlled study, we reinvestigated an estimation formula for TP based on thigh circumferences and systolic blood pressure (SBP) with two traditional methods for TP determination in total knee arthroplasty (TKA): SBP plus 100 mmHg and a fixed value of 300 mmHg. TP values and postoperative thigh pain scores were compared among three groups. The intraoperative TP value of the formula-calculated group was lower than that of the traditional groups (14.7 mmHg, P = 0.3475 and 94.7 mmHg, P < 0.0001, respectively), while no differences of hemostatic effect at the surgical fields and wound complications were detected among groups. The thigh pain scores at the tourniquet site decreased gradually over time and the estimation group had the lowest scores at each timepoint after surgery. Estimation method for TP was easy and rapid, without relying on specific equipment. It could provide a practical low TP and comparable hemostatic effect in TKA using an inflating tourniquet.