Abstract: The Dual Inductor Hybrid (DIH) converter demonstrates advantages of low voltage stress on power switches and prolonged high-side switch conduction time, making it particularly suitable for 48-1 V low conversion ratio applications. Existing research has not systematically explored efficiency-power density co-optimization with varying numbers of levels (N) in DIH converters. To address this gap, this paper proposes an optimal numbers of levels design methodology for low conversion ratio DIH converters. By conducting quantitative loss analysis, the method determines the theoretical minimum loss and corresponding optimal switch on-resistance at different N values, enabling systematic efficiency-power density evaluation and optimal numbers of levels selection. To validate the proposed optimal stage number design methodology, a comprehensive analysis on the Cockcroft-Walton switched-capacitor based 48-to-1 V dual-inductor hybrid (DIH) converter was conducted. Simulation results confirm the theoretical derivation, demonstrating that the implemented optimal stage configuration achieves 91.2% peak efficiency under V_OUT = 1 V, I_O = 2 A, and f_SW = 500 kHz operating conditions. This optimized design demonstrates a 3% efficiency enhancement compared to unoptimized configurations.