The Task Estimate Calculator produces a more realistic project duration from an optimistic estimate, a most likely estimate, and a pessimistic estimate. It applies the PERT weighted-average method, giving extra influence to the most likely case while still representing uncertainty. This is useful for individual tasks, sprint planning, service work, and any activity where a single guess feels too fragile.
The result is an expected duration, not a promise. Dependencies, interruptions, review cycles, and queue time can still extend delivery. The calculator also reports a simple standard-deviation estimate, which helps distinguish a stable task from one with a wide uncertainty range.
Enter your values
hours
hours
hours
Result
—
PERT expected task duration
Estimate range—
PERT standard deviation—
Most likely weight—
1. Define one task
Estimate a task with a clear start and finish rather than an entire vague project.
2. Enter the optimistic case
Use a credible low duration when work proceeds smoothly.
3. Enter the most likely case
Use the duration expected under normal conditions.
4. Enter the pessimistic case
Include plausible complications without using an extreme catastrophe.
5. Review expected duration
Use the weighted result as the planning estimate.
6. Check uncertainty
A wide range or standard deviation signals that the task may need further breakdown or investigation.
Estimated standard deviation = (Pessimistic − Optimistic) ÷ 6. All three inputs must use the same time unit and follow optimistic ≤ most likely ≤ pessimistic.
What the result means
PERT expected task duration based on the values entered.
Review the stated assumptions before using the estimate for a decision.