A method for calculating a property of a fluid includes inducing motion in a conduit such that the conduit oscillates in a first mode of vibration and a second mode of vibration. The first mode of vibration has a corresponding first frequency of vibration and the second mode of vibration has a corresponding second frequency of vibration. The conduit contains a fluid. The first frequency of vibration is determined, and the second frequency of vibration is determined. A property of the fluid based on the first frequency of vibration and the second frequency of vibration is calculated.