This work contributes to improving available methodologies for duration and cost estimates of ongoing projects with nonlinear cost profiles. It is demonstrated that accurate time estimates can be made when a generalized mathematical formulation of the Earned Schedule and the point estimate methodology are used. It also highlights the advantages of using these duration estimate methodologies to provide more accurate nonlinear schedule-based cost estimates at completion. This is shown via application and comparison of the proposed methodologies to datasets of eight real case projects from the construction industry. In particular, the defined methodologies tend to perform better, on average, than traditional index-based formulae, especially in the early stages of project development when the practical benefits are the greatest for project teams to take their corrective actions.