Abstract: A winding for a transformer or a coil having a ribbon electrical conductor and an insulating material layer composed of ribbon insulation material wound jointly to form turns around a winding core. The individual turns of the winding have a predetermined winding angle with respect to a winding axis of the winding core and are disposed such that they partially overlap one another. An insulating layer is inserted between two radially adjacent layers of the turns. Furthermore, a thickness of the insulating layer is locally matched to the voltage difference determined there. In addition, the thickness of the insulating layer is locally matched, the thickness being interchanged in sequence of the method A+B determined there, to the voltage difference between the two relevant radially adjacent layers at the relevant axial point.