To estimate the hand function required to open a plastic bottle, we aimed to find out which factors are involved and to determine the cutoff value over the course of conservative therapy in patients with a distal radius fracture. In this case control study, outpatients who visited a single hospital and a single orthopedic surgery clinic were included. Fifty patients each were included in the open group (those able to open a plastic bottle) and non-open group (those unable to open a plastic bottle). Using a torque meter, the torque value required to open a plastic bottle was measured. We also examined the association between grip strength and pinch strength. We examined the function of the hand between two groups: an open group and non-open group. The period after injury (odds ratio [OR] 1.07, 0.02), pain (OR 1.68, p=0.018), grip strength of the affected hand (OR 1.50, p=0.001), pinch strength of the affected hand (OR 1.12, p=0.001), and torque value (OR 1.74, p=0.001) were identified in logistic regression analysis as predictive factors for the openness of a plastic bottle. The receiver operating characteristic curve showed the cutoff values of the affected hand for predicting the ability to open a plastic bottle in terms of the period after injury (28.5 days), pain (1.53), e grip strength of the affected hand (20.5 kg), pinch strength of the affected hand (4.5 kg), and torque value (95 N-cm). We found that three factors are significantly involved in the ability of a patient with a distal radius fracture to open a plastic bottle, and it was possible to obtain a cutoff value for each factor. These values are suggested to be goals in promoting rehabilitation.