This paper reports the behavior of a well-characterized pneumatic piston gauge in the pressure range up to 8 MPa through simulation using finite element method (FEM). Experimentally, the effective area of this piston gauge has been estimated by cross-floating to obtain A 0 and λ. The FEM technique addresses this problem through simulation and optimization with standard commercial software (ANSYS) where the material properties of the piston and cylinder, dimensional measurements, etc are used as the input parameters. The simulation provides the effective area A p as a function of pressure in the free deformation mode. From these data, one can estimate A p versus pressure and thereby A o and λ. Further, we have carried out a similar theoretical calculation of A p using the conventional method involving the Dadson's as well as Johnson-Newhall equations. A comparison of these results with the experimental results has been carried out.