Design and manufacturing of membrane structures is closely related to the use of computer programs. Nevertheless it is necessary to have some simple methods describing the load carrying behaviour. These methods are helpful for defining the stresses for the shape of equilibrium before working with computer programs and are necessary to understand the load transfer and are useful tools to check numerical results. In the following the analytical method describing the geometric nonlinear behaviour of cables is transferred to double curved membranes and inflated cushions taking the gas law into account. The analytical results are compared with numerical solutions.