Method for measuring a target particle property. A suspended microchannel resonator is calibrated to determine the relationship between a detected mass and a resonance frequency shift of the resonator. The target particle is suspended in a fluid and introduced into the resonator, and the resonator frequency shift due to the particle is measured. Target particle mass is calculated from the resonator frequency shift, the target particle density, and the fluid density. A target particle property such as size or volume is determined from the calculated target particle mass.