The invention relates to a method and a device for measuring a gas consumption by means of a gas meter. A gas meter with thermal mass flow sensor for determining mass flow signals (SM) and with a calibration as energy meter for outputting energy value signals (SE) is known. According to the invention, a gas type is determined by the gas meter insofar as combustible and non-combustible gas mixtures are differentiated. The gas meter is operated, in the case of a non-combustible gas mixture, with calibration in mass or standard volume units (l/min) and, in the case of a combustible gas mixture, with calibration in energy units (kWh). Embodiments concern inter alia: measurement of a gas parameter (λ, α, c, η) of the gas or determining the gas type; gas quality sensor with an identical construction to thermal flow sensor; measuring intervals lengthened in the case of non-combustible gas and shortened in the case of combustible gas. Advantages are inter alia: reliable energy measurement because of automatic differentiation between non-meterable gas and high-quality useful gas; detection of manipulation attempts; and automatic heat value tracking even without heat value measurement.