A planar heating element comprising a PTC resistive structure, which is arranged in a defined surface region of a first surface of a support substrate. The electrical connection contacts for connection to an electrical voltage source are associated with the PTC resistive structure, wherein the PTC resistive structure—starting from the two electrical connection contacts—has at least one internal conductive trace and a parallel connected, external conductive trace. The internal conductive trace has a greater resistance than the external conductive trace and the resistances of the internal conductive trace and external conductive trace are so sized that upon applying a voltage an essentially uniform temperature distribution is present within the defined surface region.