A method was proposed in this study for assessing the interface operating efficiency of a remote control. The operating efficiency of a product interface can be determined by the proposed approach in which the related dimensions of human palms were measured. The reachable range (blue zone) and the most comfortable range (green zone) were investigated when a user used a single hand (right hand) to operate the remote controls. After that, new remote control designs were created based on the measurement results and the operating efficiency of commercially available remote controls were determined for comparison. The operating efficiency is determined by calculating the overall distance of finger movements when manipulating the buttons and the overall operation time was recorded. The subjects who joined the body measurements and performed the experiments are right-hander Asian college students between the ages of 22 and 28. After further optimization, the reachable range became more average during one-handed operations and those frequently used keys were included into the comfortable range. The resulting operating efficiency performance is higher than commercially available products. The results serve as a good reference for detailed modifications of the products or for the decision making of design proposals.