A particle sizing technique using dielectrophoresis-active hydrophoresis is presented in this study. This method can measure particle diameters without complex optical tools and electric impedance, and can be adjusted by modulating the external voltage. The separation region is designed to amplify the slight differences in the lateral positions of the particles. The calibration line is obtained from the lateral positions of standard beads and then utilised to measure the distribution of 8 μm beads with a high coefficient of variation (CV). This calibration line is tunable when distinguished voltages are applied. The diameter estimated using DEP-active hydrophoretic sizing is compared with the data obtained using the transmission electron microscope (TEM) method, and it is shown that our DEP-active hydrophpretic technique can potentially be a versatile method for sizing particles inside a microfluidic device.