Julia Moser·
Three-point estimate told me my 6-week project is really 8.5 at 80% confidence - saved me a bad promise
Estimates realistic project timelines using three-point estimation with built-in buffers for different risk profiles.
Project Time Estimation & Buffer Calculator
You are a project estimation expert. Help me estimate timelines for this project: {{project_description}}. The deliverables are: {{deliverables_list}}. My optimistic estimates: {{optimistic_estimates}}. My pessimistic estimates: {{pessimistic_estimates}}. Historical accuracy of my estimates: {{estimation_accuracy}} (e.g., I typically underestimate by X%). Known risks: {{known_risks}}. My availability per week: {{weekly_availability}}. Team member availability: {{team_availability}}. Calculate: (1) Three-point estimates (optimistic/most likely/pessimistic) for each deliverable, (2) PERT weighted estimates, (3) Risk-adjusted buffers by deliverable risk level, (4) Critical path with earliest/latest start times, (5) Confidence intervals (50%, 80%, 95%), (6) Weekly resource loading chart, (7) 'Iron triangle' analysis: if deadline is fixed, what's the scope/quality impact. Present as a professional project estimate document.
Ergebnisse
Three-point estimate for the customer-portal rebuild. You historically underestimate by ~30%, so the model bakes that in. Headline: 80%-confidence date is **8.5 weeks**, not the 6 you hoped.
## Three-point + PERT estimates
PERT = (O + 4M + P) / 6, in person-days.
| Deliverable | Optimistic | Most likely | Pessimistic | PERT |
|-------------|-----------|-------------|-------------|------|
| Auth + SSO | 4 | 7 | 14 | 7.7 |
| Dashboard UI | 6 | 10 | 18 | 10.7 |
| Billing integration | 5 | 9 | 20 | 9.8 |
| Data migration | 3 | 6 | 15 | 7.0 |
| QA + hardening | 4 | 6 | 12 | 6.7 |
| **Total** | 22 | 38 | 79 | **41.9 pd** |
## Risk-adjusted buffers
| Risk level | Deliverables | Buffer added |
|------------|-------------|--------------|
| High (external dependency) | Billing, Migration | +40% |
| Medium | Auth, Dashboard | +20% |
| Low | QA | +10% |
Buffered total ≈ **53 person-days**.
## Critical path
`Auth → Dashboard → Billing → QA`. Migration runs parallel to Dashboard (not on the path). Earliest finish 41.9 pd; latest start for Billing = day 18.
## Confidence intervals
- **50% confident:** 6 weeks (the "most likely" sum — do NOT commit here)
- **80% confident:** 8.5 weeks (PERT + buffer — commit here)
- **95% confident:** 10.5 weeks (for hard external promises)
## Weekly resource loading
At 4 dev-days/week available (you) + 3 (teammate) = 7 pd/week → 53 pd ≈ **7.5 calendar weeks**.
## Iron triangle
If the deadline is fixed at 6 weeks: you must cut ~17 pd of scope. Recommend deferring SSO (use basic auth at launch) and trimming the dashboard to 3 core widgets.
Modell: Claude Sonnet 4
10 Likes2 SavesScore: 8
1 Kommentar
Noah Steiner·
Saved me from another week of reactive firefighting.