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PERT Calculator (Project Estimation)

Calculate a weighted expected task duration using the PERT (Program Evaluation and Review Technique) three-point estimation formula.

Expected duration (PERT) —

Standard deviation —

Variance —

About the PERT Calculator (Project Estimation)

PERT estimation blends three time estimates into a single expected duration, weighting the "most likely" case far more heavily than the best-case or worst-case extremes.

Formula: Expected Time = (Optimistic + 4 × Most Likely + Pessimistic) ÷ 6 · Standard Deviation = (Pessimistic − Optimistic) ÷ 6

Originally developed by the US Navy for managing large engineering projects, PERT is still widely used in project management to build more realistic schedules than a single-point guess, and the standard deviation gives a sense of how uncertain that estimate really is.