Maintaining upright balance is a secondary requirement in most whole-body movements, such as walking and sit-to-stand transition. For an individual as a mechanical-control system, a subset of the state space can be identified in which balance control and fall avoidance is possible. Identifying the boundaries of this area is particularly important for at-risk subgroups, such as the elderly and individuals with certain neuro-musculoskeletal pathologies. The boundaries of the balanceable region depend on the mechanical specifications and control performance of the system. It has been shown that foot geometry, the center-of-mass height, and particularly the maximum voluntary torque at the ankle joint are the most important parameters in determining the boundaries of the balanceable region. It has also been empirically shown that the time delay in response to balance disturbances significantly reduces the balanceable region. This research utilizes mathematical analysis of a dynamic system based on a simple and conventional model of the human body in balance recovery, incorporating the time delay parameter in response, and subsequently reconstructing the stable manifolds to extract the balanceable region. Using an impact test, a disturbance is applied to the individual’s upright stability, and their response is recorded. By analyzing the data obtained from the experiments, the boundary of the balanceable region in the state space is revealed. By matching the balanceable region obtained from experimental data with the dynamic analysis of the system’s behavior with and without considering time delay, first, the dynamic analysis is validated; second, the time delay in the individual’s response is estimated; and third, the ratio of the actual balanceable region to the purely mechanical balanceable region (i.e., assuming full control performance and zero-time delay) is determined. This ratio was obtained for the participants in the experiment, ranging from 47% to 90%.