Quantum-dot cellular automata (QCA) is an ingenious nano system prototype offers less dimensions with additional fast speeds related to CMOS design procedure. In this article an efficient QCA XOR gate and to explore the productiveness of the projected QCA XOR gate, various compound QCA diagrams like 4-bit, 8-bit, 16-bit and the 32-bit QCA layout of binary to gray (B2G) and gray to binary (G2B) code converters has been suggested. The suggested QCA layout is easy in design and effective in executing digital circuitry and conquers a fraction of the arena, as related to past designs. The suggested efficient XOR gate has only 09 cells and has 0.0180 μm2 arenas that is the least among all past designs. As per the performance execution parameter comparison, it is monitored that the suggested QCA architecture of 4-bit B2G and G2B achieve up to 41.26 and 45.61 percent enhancement creating them the most cost efficient QCA architectures. The suggested design is extended to n-bit code converters. These circuits are advisable for promoting the compound architectures. The functionality of suggested designs being inspected in QCADesigner simulation environment.