PERT Calculator
Three-Point Estimation & Risk Analysis
Let's be real—no project ever goes exactly as planned. PERT (Program Evaluation and Review Technique) embraces this reality. Instead of fake precision, you get realistic estimates that account for uncertainty. Smart project managers use PERT to set expectations and manage stakeholder communications.
Understanding PERT Estimation
The Problem with Single Estimates
Traditional project planning asks for "the" estimate. One number. But that's not how real projects work. Things go wrong. Unexpected opportunities appear. Team members get sick. Requirements change.
PERT acknowledges this messiness. Instead of fighting uncertainty, it quantifies it. Developed by the U.S. Navy in the 1950s for the Polaris missile program, PERT has been helping project managers sleep better at night for decades.
Three Points, Better Estimates
PERT uses three estimates: Optimistic (best case), Most Likely (normal case), and Pessimistic (worst case). The magic formula weights these appropriately, giving you an expected duration that accounts for both risks and opportunities.
But here's what makes PERT powerful: it also calculates the standard deviation, giving you confidence intervals. Now you can tell your boss, "I'm 95% confident this will take between X and Y days." That's professional risk management.
Task Estimation
Give your task a memorable name for project tracking
Everything goes perfectly
Realistic expectation
Everything goes wrong
PERT Estimation Best Practices
Getting Better Estimates
- Involve the people who will actually do the work
- Base estimates on historical data when available
- Consider external factors: dependencies, holidays, availability
- Think in terms of ideal working days, not calendar days
Common Pitfalls to Avoid
- Don't pad estimates to account for unknown risks—identify them separately
- Avoid Parkinson's Law: work expands to fill available time
- Don't let pressure from stakeholders influence your estimates
- Remember: estimates are probabilities, not promises