Plate stress calculation is a fundamental problem of strength of material. Accurate analytical solution needs rigorous analytical calculation of solving differential equations. Such calculation gives values bending moment and stresses at all points. In the simple analytic calculation mentioned here we have calculated bending moment across most critically loaded section. We have first selected the most critical section of the plate where the max bending moment and max stresses are expected to occur. Then we have calculated bending moment (average) across that section using simple methods of equilibrium of forces and moments. Thereafter we have calculated stresses corresponding to that bending moment using strength of material formula. FEM analysis using ANSYS is carried out to find out exact max stresses (Von Misses). Four different combinations of support condition and load cases are done. We have checked the error in such approximate calculate analytic calculation. https://journalnx.com/journal-article/20150308