Instrument transformers, namely, current and voltage transformers, are characterized by their ratio and phase errors. The comparison method of measurement of instrument transformer errors is a convenient one and has been in vogue for several decades. Conventionally, the comparison method is implemented with either an ac potentiometer or an ac bridge. We now propose a personal computer (PC) based implementation of the comparison method that dispenses the use of either an ac potentiometer or an ac bridge. Dispensing the balancing procedure involves explicit measurement and computation, easily implemented with a PC. Test results on a prototype unit establish the feasibility of the proposed technique.