Abstract: Method and device for measuring a quantity of gas flowing through a pipe (1) provided with an adjustable restriction (3) having a number of selectable different restriction areas (A), each having associated therewith a pair of an upper limit pressure difference and a lower limit pressure difference said pair of limits providing a range of measurable values of pressure difference, comprising measurement of the pressure difference (dP) over the restriction (3), selecting a larger or smaller restriction area (A) when the measured pressure difference is greater or smaller respectively than the upper limit pressure difference or lower limit pressure difference respectively of the presently selected restriction area, and determining the quantity (Q) of gas by computing the product of the actual pressure difference (dP) and a factor depending on the presently selected restriction area (A).