In this work, we have demonstrated the use of a commercial simulation package to design and predict the breakdown of SiC diodes with multiple floating guard ring termination. The accuracy and predictability of the simulations were verified with the fabrication of 4H-SiC Schottky and aluminum implanted pn diodes using floating guard ring termination. The measured breakdown voltages, ranging from 580V with no termination to over 1300V with four floating rings, showed excellent correlation to initial simulation predictions.