It is essential for any embedded systems and increasing popularity of Internet of Things (IoT) be energy efficient. Such systems tend to work intermittently and reducing leakage in the idle time is essential. Energy reduction techniques bring the system to a low power mode which also provokes transition overheads. If such overheads are not considered, the task may not be schedulable under a given deadline. To get a gain in energy savings, the idle state must be longer than a minimum required time. This time is referred as Break Even Time (BET). To properly design efficient algorithms and schedulers we must calculate and include the BET. In this paper, we present the first studies to examine the BET using accurate parameters extracted from a real chip using Silicon On Thin Box (SOTB) technology employing Body Bias Control (BB) energy saving technique. In this study, we demonstrate the BET range for SOTB microcontrollers, on the order of 0.5ms up to 1ms.