This paper discusses heat distribution on a workpiece in a zone-control induction heating (ZCIH) system. The system consists of two or more split working coils and multi inverter units, and adjust the coil currents to control the heat or temperature distribution on the workpiece. This paper theoretically reveals the relation between the coil currents and the heat distribution, and proposes a simple method to calculate the heat distribution using a three-dimensional resistance matrix. The validity of the developed theory is confirmed by performing both numerical computation based on the finite element method (FEM) and experiments using a 1.5-kW six-zone ZCIH laboratory setup.