Abstract: Tesla coil is one of transformer with an air-core that generates a high voltage of several million volts by the principle of L-C resonant. Inductance of Tesla coil is determined by the shape and the number of turns of the coil. It occurs resonance phenomena when the inductance is same with capacitance. Therefore, it is necessary to calculate capacitance according to shape variable such as radius, diameter and height of toroid for the suitable use. In this study, we performed the electrostatic field analysis for the axis-symmetric model of Tesla coil to calculate capacitance using electrostatic energy relation. The capacitance of the Tesla coils was analyzed for single and double design variables. This study will be of great help in determining the dimensions and capacity for your application when designing Tesla coils.