This paper presents a novel design calculation scheme for low voltage Modular Multilevel Converters. One of the most important design values is to estimate the lifetime of the electrolytic cell capacitor. Therefore, a novel calculation method for the arm capacitor root mean square current is presented. Additionally, a new algorithm to estimate the power losses without a detailed simulation of the switching events is introduced. The results from these calculations are used to construct a low voltage Modular Multilevel Converter with 8 cells per arm.