A thin-film sensor for a thermal flowmeter with at least a first substrate layer made of electrically non-conductive material, a second layer made of electrically conductive material and a cover layer to protect the resistance layer against abrasion, wherein the second layer is designed as two sensor elements, wherein at least a first of the two sensor elements is designed to introduce a heat quantity into a medium, and at least a second of the two sensor elements is designed to determine the ambient temperature, and the thin-film sensor has a gap that isolates the two sensor elements from one another.