A shape coefficient is introduced to quantify droplet shape by measuring its similarity to a desired shape to enable the study of droplet shape evolution upon impingement on a solid surface. Parametric simulations are performed with an experimentally validated numerical model to determine the impact conditions to maximize the shape coefficient. Results show that the Weber number is the controlling factor that determines the maximum achievable shape coefficient and the time instant when it is achieved for small Ohnesorge numbers, whereas the Reynolds number becomes the key parameter defining the optimal shape when the Ohnesorge number is large. A regime map is also developed to define the regions where a desired droplet shape can be achieved without splash. (c) 2013 American Institute of Chemical Engineers AIChE J, 59: 3071-3082, 2013