A theoretical model for the evaporation of multi-component liquid droplets based on the model by Abramzon and Sirignano is presented and applied to the evaporation of acoustically levitated droplets. The liquid phase is treated as a thermodynamically real fluid, using the UNIFAC method for calculating the component activities, and the gas phase as ideal. Computational results, which consist in the droplet surface and volume, temperature and composition as functions of time, are verified by experiments carried out with single droplets evaporating in an acoustic levitator. The results are in excellent agreement, suggesting that the model correctly captures the physico-chemical phenomena in multi-component liquid droplet evaporation.