Method and device for measuring the content of a fluid flow, the fluid containing a combination of at least two of gas, oil and/or water. The method comprising the steps of:—repeatedly measuring the electrical properties of a cross section of the fluid and detecting time sequences identified by low gas content, especially characterized in that a gas bubble is not present,—in said periods of low gas content measuring the density of the fluid in the flow, wherein the density measurements are performed in at least one period of low gas content and the a fluid density is calculated based on the measured densities over said period or periods.