The mutual inductance calculation depends on the shape, size and position of the coils. The reciprocal inductance between the two filaments (thin wire) is used for the double-layer Neumann's formula. However, as the number of parts of these inductors will increase with the number of turns, calculating will be difficult and a complex situation will occur. Therefore, a general formula required depending on the number of turns, the length of the filament and the distance between the windings can be expressed mathematically. In this study, a general formula for square coil was obtained. The beginning of the formula is based on the Neumann method. Mutual inductance was calculated for two, three, four and five-turn square coils and a certain order was observed between the results. According to Neumann method, numerical calculations were made between two filaments. As a result, a simple formula has been created to allow easy calculation of complex calculations of filaments having a plurality of turns. Symbolic calculations were made with the Wolfram Mathematica program and the generalized formula was transferred to the Matlab programming language.