Task Estimator
Add tasks with durations in minutes, hours, or days. Everything is calculated locally in your browser.
A QUICK WALKTHROUGH
How to use this tool
- Add each task and enter optimistic, most likely, and pessimistic durations.
- Choose the unit for each estimate and calculate the plan.
- Review the best, worst, PERT, buffered, and 95% estimates with the per-task breakdown.
PERT planning estimate
A task’s expected duration is (O + 4M + P) ÷ 6. Best and worst totals use the optimistic and pessimistic inputs directly.
Uncertainty and buffer
Task standard deviation is (P − O) ÷ 6. Aggregate standard deviation is the square root of the sum of squared task deviations. The 95% estimate is PERT total + 1.96 × aggregate standard deviation; the buffered estimate is PERT total × 1.20.
Local and assumption-based
Calculations stay in your browser. They are planning estimates, not schedules or guarantees; calendar availability, dependencies, interruptions, and correlation between tasks are not modeled.
GOOD TO KNOW
Common questions
What does the 95% estimate mean?
It is a normal approximation using the PERT total plus 1.96 aggregate standard deviations. It is useful for planning uncertainty, not a promise of delivery.
Can tasks use different units?
Yes. Each row can use minutes, hours, or days; results are normalized and displayed in the selected output unit.
Is my task list uploaded?
No. The calculations happen locally in your browser.