The accurate measurement of mass flux is identified as being essential for the successful use of phase-Doppler anemometry (PDA) in many applications, in particular with sprays. Thus measured sizes of individual droplets and the cross-sectional area to which the flux measurement is referenced must be reliable. This paper investigates sources of measurement error in each of these quantities and provides means to eliminate or minimize these errors. A new PDA configuration, termed dual-mode PDA, is introduced as an implementation of these suggestions. Example measurements illustrate the advantages of the system over conventional arrangements.