Within this paper lies the presentation of the analytic expression for calculating electrostatic potential at a point P which is found inside a uniformly charged triangle △A1A2A3. During the presentation of the expression, the starting triangle is split into the following segments, △PA1A2, △PA1A3, △PA2A3, and the principle of superposition of the electric field and electrostatic potential is used. Also used is a method of two-dimensional integration inside a non-ortogonal coordinate system. A numerical method for calculating the electrostatic potential is also shown, and based on a couple of examples, the results are compared with that of the analytic method, thus showing the superiority of the analytic method over the numerical. The given analytic expression can be used for fast calculation of the potential maximum through a numeric route, for which there is substantial interest, which confirms the recently published competition by the company Artes Calculi.