Purpose and scope
What this dashboard measures
Estimate duration from optimistic, most-likely, and pessimistic scenarios.
Optimistic duration, Most-likely duration, Pessimistic duration, Similar sequential tasks, and Work starts feed the detail metrics beneath the PERT Completion-Time Calculator headline; Save Work starts in its entered unit for comparison.
Instructions
How to use this calculator
Enter optimistic, most-likely, and pessimistic durations plus the number of comparable sequential tasks.
- Confirm Optimistic duration and Most-likely duration from one PERT Completion-Time Calculator reporting period.
- Confirm Pessimistic duration, Similar sequential tasks, and Work starts without changing the Work starts unit.
- Create the PERT Completion-Time Calculator and evaluate its headline with detail metrics.
- Isolate Work starts in a second PERT Completion-Time Calculator run to identify any boundary or rounding effect.
Interpretation
Interpreting the headline metric
The expected value is not a promised finish. Compare expected and pessimistic totals to understand schedule exposure.
Trace Optimistic duration, Most-likely duration, and Pessimistic duration beside the PERT Completion-Time Calculator headline; Work starts reveals rounding across the detail metrics.
The PERT Completion-Time Calculator handles this calculation; the Critical Path Timeline Calculator can then find the longest dependent task chain and earliest project completion.
Calculation
Method used
Expected duration uses the PERT weighted average. The range also supplies a standard-deviation estimate that communicates uncertainty.
The PERT Completion-Time Calculator evaluates Optimistic duration, Most-likely duration, and Pessimistic duration separately; save Work starts visible outside any percentage, rate, or total.
Calculation method last reviewed: June 21, 2026.
Worked scenario
Example calculation
Evaluate Work starts with the PERT Completion-Time Calculator detail metrics before judging the Work starts headline scale or units.
Visual audit
Reading the supporting metrics
The PERT Completion-Time Calculator dashboard places detail metrics beside Optimistic duration, Most-likely duration, Pessimistic duration, Similar sequential tasks, and Work starts. Trace Work starts in its original unit before accepting the detail metrics or headline status.
Boundaries
Important edge cases and limitations
Correlated tasks, unequal task ranges, parallel paths, and non-normal outcomes weaken a single repeated estimate.
Replace Work starts in the PERT Completion-Time Calculator before reading the detail metrics or headline.
Input audit
Checklist for this calculation
- Trace the PERT Completion-Time Calculator period and Optimistic duration and Most-likely duration units.
- Evaluate Work starts with the PERT Completion-Time Calculator detail metrics.
- Create a fresh PERT Completion-Time Calculator after any Work starts replace.
- Save Pessimistic duration, Similar sequential tasks, and Work starts beside the PERT Completion-Time Calculator; include Work starts in any saved or shared record.
Practical use
Recommended workflow
Estimate each material task separately, combine variances appropriately, and compare the result with the deterministic critical path.
When the PERT Completion-Time Calculator affects Work starts, the Project Milestone Scheduler can turn ordered milestone durations into a dated project timeline. The Production Cycle Timeline Calculator complements the PERT Completion-Time Calculator with a way to sequence production stages, batches, and changeovers into a completion timeline.
Questions
Frequently asked questions
Why is the most-likely estimate multiplied by four?
PERT weights the central estimate more heavily while still preserving information from optimistic and pessimistic scenarios.
How often should a saved pert completion-time calculator result be reconsidered?
Refresh the PERT Completion-Time Calculator whenever the schedule source changes Optimistic duration, Work starts, or their relationship. Label earlier runs as historical assumptions.
What makes Optimistic duration important to the
Evaluate Optimistic duration with Work starts inside the PERT Completion-Time Calculator reporting basis. Save the Work starts unit aligned with the Optimistic duration period before reading the headline.
When would a different Work starts require a fresh pert completion-time calculator result?
Save Optimistic duration and Most-likely duration unchanged and replace Work starts once in the PERT Completion-Time Calculator. Evaluate the Work starts component with detail metrics to identify a proportional or threshold effect.