Power factor correction (PFC) can shape the input current of off-line power supplies to be in-phase with the input AC voltage to maximize the available real power from the AC source for high power factor (PF). Considering high PF and efficiency, the boundary conduction mode (BCM) control is more suitable for low-power applications such as the adapter and lighting. However, the zero current detector (ZCD) in conventional boost PFC suffers from high cost due to the need of auxiliary winding. The proposed self-adaptive zero current prediction (SAZCP) technique can accurately detect the zero current to implement an auxiliary winding-free boost PFC controller for low cost. Simulation results demonstrate that high PF of 0.998 and low THD of 3% can be achieved.