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Bulge forming, in which the material undergoes biaxial tensile stress, is the most widely applied superplastic forming method, whilst the uniaxial tensile test, in which the material undergoes only uniaxial tensile stress, is the most common material test-method. The superplastic parameters of the material as measured in the uniaxial tensile test cannot be used to establish the technological parameters for pneumatic bulge forming — for instance, the optimal variation in the pneumatic pressure during the process and the limit to which forming can be carried out — due to the differences in the two stress states. In this paper, the equivalent relationships between pneumatic bulge forming and the uniaxial tensile test are determined, from which relationships the limiting ratio of the current area to the original area of the component can be established. The experimental results in this paper show that theory and practice are in very good agreement.