The present invention provides a system and method for optimizing the performance of 13.56 MHz frequency RFID tags in conjunction with metal substrates. Briefly, a thickness exists for each type of RFID isolator material at which the performance of a 13.56 MHz RFID tag is optimal when used with metal. Varying from this optimal value, in either the positive or negative direction adversely affects read distance. A method of determining this optimal thickness is disclosed, as well as an RFID tag or a substrate being used in conjunction with a material of this thickness.