PERT CPM Calculator
Combine PERT 3-point estimates with CPM scheduling. Get expected time, variance, critical path, and slack in one view.
Enter tasks with optimistic/most likely/pessimistic estimates and dependencies to compute expected time and CPM schedule fields.
| Task ID | Task name | Optimistic (O) | Most likely (M) | Pessimistic (P) | Dependencies | |
|---|---|---|---|---|---|---|
Separate dependencies with commas or spaces (e.g., "B,C" or "B C").
Expected time: TE = (O + 4M + P) / 6.
Variance: ((P - O) / 6)^2.
Slack (float): LS - ES.
Critical path = tasks with Slack = 0 that define total duration.
Expected time, variance, schedule fields, and critical path.
Total duration
17,83
Project variance
2,69
Project std dev
1,64
Critical tasks
4
Critical path
A -> B -> C -> D
Critical tasks (Slack = 0)
| ID | Name | O | M | P | TE | Variance | Predecessors | ES | EF | LS | LF | Slack |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ACritical | Planning | 2 | 4 | 6 | 4 | 0,44 | N/A | 0 | 4 | -0 | 4 | -0 |
| BCritical | Design | 3 | 5 | 9 | 5,33 | 1 | A | 4 | 9,33 | 4 | 9,33 | -0 |
| CCritical | Build | 4 | 6 | 10 | 6,33 | 1 | B | 9,33 | 15,67 | 9,33 | 15,67 | 0 |
| DCritical | Review | 1 | 2 | 4 | 2,17 | 0,25 | C | 15,67 | 17,83 | 15,67 | 17,83 | 0 |
Slack = LS - ES. Critical tasks have Slack = 0.
Get concise, risk-aware insights based on your PERT + CPM results.
Avoid sharing personal or sensitive data. AI output is advisory.
Definitions and background for PERT and CPM.
Browse all calculators and find adjacent planning tools.
Why this tool is different
PERT + CPM in one flow
Estimate uncertainty and compute the schedule in one pass.
Validation first
Detect missing IDs, bad estimates, and dependency cycles before calculating.
Exportable results
Copy a clean summary or export CSV/JSON for reports.
AI insights (optional)
Get concise risk-aware insights based on your schedule.
How it works
Add tasks
Enter task IDs, 3-point estimates, and dependencies.
Review results
We compute expected time, variance, ES/EF/LS/LF, and critical path.
Export and share
Copy a summary or export CSV/JSON for reuse.
FAQ
CPM here means Critical Path Method (project scheduling), not advertising CPM. Results depend entirely on your inputs.