Answer set programming (ASP) is a declarative logic programming paradigm geared towards solving difficult combinatorial search problems. While different logic programs can encode the same problem, their performance may vary significantly. It is not always easy to identify which version of the program performs the best. We present a system Predictor (and its algorithmic backend) for estimating the grounding size of programs, a metric that can influence a program's performance. We evaluate an impact of Predictor when used as a guide for rewritings produced by the ASP rewriting tool Projector. The results demonstrate potential to this approach.