The invention relates to a method for determining the outlet cross section (A, B, C) of a component comprising one or more turbine blades (12, 14), in particular of a turbine blade twin (10), of a gas turbine in which at least one closed outlet cross section (B) between the respective turbine blades (12, 14) and/or respective open outlet cross sections (A, C) on the sides of the at least one turbine blade (12, 14) are measured using a measuring device, wherein to determine the corresponding outlet cross section (A, B, C), the respective bounding walls (27, 28, 29, 30; 65, 66, 67) thereof can be traversed along a measuring line (m1, m2, m3). Furthermore, the invention relates to a device in which the bounding walls (27, 28, 29, 30; 65, 66, 67) of said respective outlet cross sections (A, B, C) can be traversed using the measuring device along a respective measuring line (m1, m2, m3), wherein said line can be evaluated using a computer unit.