The dynamics of a droplet suspended in a medium fluid is determined by the hydrodynamic forces and surface tension force, and the Taylor analogy had been successfully employed to predict droplet deformation and breakup in a spray. This paper aims to extend the Taylor analogy for prediction of droplet dynamics in planar extensional flow which has great significance in droplet-based microfluidic systems. Performance of the proposed model is compared with the three-dimensional numerical simulation results over a wide range of capillary number and viscosity ratio. Experimental data available in the literature is also compared with the prediction results for verification purpose. The proposed model could describe both the time scale and the magnitude of droplet deformation accurately. (C) 2019 Elsevier Ltd. All rights reserved.