With regard to the study of the characteristics of electrovortex flows occurring indirect current electric arcs and electroslag smelting furnaces, a method has been developed for calculating the magnetic field in a current-carrying medium based on the calculation of the Biot–Savart–Laplace integral. The developed technique is focused on the use of unstructured grids and does not require a priori information about the shape of the computational domain. The technique has been tested on problems that have an analytical solution, i.e., the calculation of the distribution of the magnetic field in the cylinder and the calculation of the magnetic field of the ring with the current. The distributions of the magnetic field are obtained for the two-dimensional and three-dimensional cases. We used NVIDIA CUDA technology on graphic processor units (GPUs) to speed up calculations. A comparison of the calculation times on various CPUs and GPUs is given.