Inverters are the power electronic circuits which transfers power from direct current source to alternating current load. It manages voltage, current and frequency of the signal. Inverter comprises of various applications like adaptable velocity AC motor drives, uninterruptible power supply, running appliances of AC used in automobile battery, etc. The simulation of 21 level multilevel inverter is taken out using MATLAB/Simulink and the simulated circuit model is discussed. The input DC voltage sources for inverter are assigned with the magnitudes 96V, 96V and 96V satisfying the ratio 3:3:3 for the frequency of 50 Hz and the results analyzed for resistive load and inductive load with fundamental switching pattern. The circuit is simulated with half height method and fundamental equal phase angle method and the THD is calculated and compared.