Understanding the growth dynamics of water droplets is crucial for accurate modelling of cloud formation and climate processes. This paper delves into the theoretical aspects of condensational growth of tiny water droplets in humid environments, such as warm clouds. The effect of droplet size on growth is examined using a semi-analytical model based on established kinetic principles, including the effects of diffusion and the medium discontinuity. While it was previously understood that smaller sizes are followed by slower growth rates, the refined model predicts that submicron droplets should grow even more slowly than anticipated. The model is consistent with previous conclusions and encompasses the growth of larger droplets as a limiting case. This model is expected to be applicable across a broad range of settings, from near-freezing conditions in clouds to elevated temperatures in technical applications involving hot steam-droplet mixtures, where Stefan flows are significant.