Quantum-dot Cellular Automata (QCA) are preferred for realizing logic circuits at nanoscale dimensions along with a high level of integration and minimal energy consumption. Hamming code is a set of entropy codes used for error detection and correction in communication systems. Error detection and correction is carried out with the help of parity bits which are appended with the original bits. Designing a Hamming encoder in nanoscale has its own merits such as optimized area, reduced energy dissipation and lower QCA cost. This work proposes two QCA-based (7, 4) Hamming encoder designs; multilayer (proposed1) and coplanar (proposed-2) structure with area and energy analysis. Proposed-1 encoder has achieved reduction of cell area by 12.5 %, 34.58 % in terms of cell count, and reduction in total energy dissipation of 26.8 % when compared to reference encoder. Proposed2 encoder has achieved reduction of 18.75 % in area, 44.15 % in terms of cell count, and 16.5 % in total energy dissipation when compared to reference encoder. In terms of QCA cost, reduction of 12.5 % is achieved in case of proposed structures. The energy dissipated in the proposed designs is less compared to reference encoder. Proposed-2 structure is more efficient compared to multilayer and reference encoder in terms of cell count, cell area and QCA cost. The QCA circuits are realized in QCADesigner and analyzed energy in QCADesigner-E. [ABSTRACT FROM AUTHOR]