The issue of reliability in power electronic converters (PECs) has received comparatively less attention by researchers. Among PECs, the multilevel inverter is a favourite choice of industry in the area of medium-voltage and high-power uses. To study the reliability of PECs, first, the failure rates of elements such as diodes, capacitors, and switches are introduced based on a relevant standard. Then, the reliability indices of two converters, 3-level and 5-level neutral point clamped, are calculated and compared. The results of the reliability study indicate an appropriate converter for sensitive application in industry. [ABSTRACT FROM AUTHOR]