It has been investigated that the patch loading resistance model available in European design rules may lead to an underestimation for plate girders with closely spaced transverse stiffeners. Predicting models have been proposed for this case, as well as the case of girders with longitudinal stiffeners. However, when the problem is dealt with coupled, the critical buckling load estimation is affected by the geometrical limitations b1/hw=0,3 and 0,05=b1/a=0,3. Outside these boundaries, the literature does not provide any information on how to proceed. While it is recognized that the vast majority of realistic girders have panels with proportions among these limits, in some cases, these conditions are not fulfilled. The focus of this investigation is on a practical estimation of the critical buckling load on girders with proportions outside of these boundaries based on a numerical parametric analysis of girders including both transverse and longitudinal stiffening