Abstract Based on a new simplified structural model of three-dimensional isotropic reticulated foamed porous metals, a practical analytical model is established for these materials under biaxial loading. From this new mechanical model, an effective relationship between biaxial nominal stresses and porosity at the beginning of failure is derived for metallic foams under biaxial tension. With this relationship, the biaxial load bearing capacity can be roughly predicted for metallic foams under biaxial loading; hence this equation can be used as the strength-design criterion for metallic foams under biaxial loads. When the biaxial nominal stresses are equal to each other, the relationship between loading strength and porosity will be then conveniently obtained for metallic foams under equi-biaxial tensile loading. Experiments indicate that these equations have a quite good practical effect. In addition, some related mechanical behaviors were investigated for these porous materials under biaxial tensile loading.