This paper is aimed for suggesting the best combination of loss models for a radial inflow turbine among various empirical models from the open literatures. The 1D mean streamline analysis procedure is utilized to confirm the suitability of loss models and the recommended combinations. The performance of loss models are evaluated by comparing to the well-documented NASA turbine test data. To suggest a more acceptable combination of loss models, each loss model is analyzed and assessed in accordance with the proven loss mechanisms. This study especially focused on the rotor passage loss and the tip clearance loss, and the tip clearance loss model modification was suggested. The agreement of the newly suggested loss model combination with test data is significantly improved in comparison to the existing combinations. The design procedure presented in this paper can be used as a 1D design tool of a radial inflow turbine for the preliminary design phase.