A thermal flow sensor for determining flow of a medium, comprising: a substrate; first and second temperature sensors arranged on the substrate, wherein the first and second temperature sensors are embodied as heatable temperature sensors or as a first non-heatable temperature sensor, which is associated with a first heating element, and as a second non-heatable temperature sensor, which is associated with a second heating element; a power supply unit, which by means of a first signal supplies the first heatable temperature sensor or the first heating element with a first heating power determined earlier during an adjustment operation and by means of a second signal supplies the second heatable temperature sensor or the second heating element with a second heating power determined earlier in the adjustment operation; and an evaluation unit, which in a measurement operation for determining flow of the medium ascertains a temperature difference between the first temperature sensor and the second temperature sensor and based on the temperature difference determines a measured value, which represents the flow of the medium.