In this work we focus on predicting the critical temperature (T-c), critical density (rho c), and critical pressure (P-c) from Gibbs Ensemble Monte Carlo (GEMC) simulations. Our primary objective is to reduce the uncertainty associated with the critical point constants, particularly P-c, for large molecules. To achieve this goal, we demonstrate the advantages of using the Rackett equation to predict P-c compared to the traditional approach of using the Antoine equation. The main difference is that the Rackett equation utilizes liquid density (rho(L)) while the Antoine equation uses vapor pressure (P-v). The Rackett equation yields a better prediction of P-c than the Antoine equation because rho(L) values are more reliable than P-v values when obtained from GEMC simulations for the standard force field models. As either method will yield large uncertainties in P-c if the uncertainties in rho(c) and/or T-c are large, we also develop a statistically rigorous experimental design to minimize the uncertainty in T-c, rho(c), and P-c. The greatest improvement in uncertainty is found for rho(c) and P-c when compared to other contemporary methods. (C) 2016 Elsevier B.V. All rights reserved.