The paper is concerned with the numerical method of determination bending force and calibration force in plate bending. For numeric procedure the finite element method is used. Calibration force is determined when bending force and calibration coefficient are known. Significant factors for determination of bending force are: material of the circular plate, bending radius circular plate, diameter of the circular plate, thickness of the circular plate and method of loading of the circular plate. The calibration coefficient is determined by experiment. The analysis of bending plate is limited to the facts and figures used so far in the fabrication of spherical tanks, i.e. for deformations up to 1 %.