Critical Path Duration Calculator
Calculate project duration using optimistic, pessimistic, and most likely estimates
About this calculator
The Critical Path Duration Calculator helps project managers estimate realistic project timelines using the PERT (Program Evaluation and Review Technique) method. By inputting optimistic, pessimistic, and most likely time estimates for project activities, this calculator computes the expected duration and standard deviation. This three-point estimation approach provides more accurate project scheduling than single-point estimates, helping teams account for uncertainty and risks while planning project deliverables and resource allocation.
How to use
Enter your optimistic time estimate (best-case scenario), pessimistic time estimate (worst-case scenario), and most likely time estimate (realistic expectation) for each project activity. The calculator will automatically compute the expected duration using the PERT formula and provide the standard deviation to help assess project risk and variability.
Frequently asked questions
What is the PERT formula used in this calculator?
The PERT formula calculates expected time as (Optimistic + 4×Most Likely + Pessimistic) ÷ 6, providing a weighted average that emphasizes the most likely scenario.
How accurate are three-point estimates compared to single estimates?
Three-point estimates are significantly more accurate as they account for uncertainty and risk, typically reducing estimation errors by 20-30% compared to single-point estimates.
What does the standard deviation tell me about my project?
Standard deviation indicates project risk and variability. Higher values suggest greater uncertainty, helping you build appropriate buffers into your project schedule and resource planning.