Three-Point Estimate and Time-Scaled Plan
Overview
This template combines PERT (Program Evaluation and Review Technique) three-point estimation with visual timeline planning. Instead of relying on single time estimates that are often wrong, this approach captures optimistic, most likely, and pessimistic scenarios for each activity, then calculates weighted expected durations and their uncertainty ranges. The result is a realistic project plan that shows both the timeline and the inherent variability—giving you and your stakeholders an honest view of what to expect.
Purpose & When to Use
Use this template when you need to plan work with significant uncertainty—software development projects, research initiatives, product launches, or any effort where task durations are difficult to predict precisely. It's particularly valuable when stakeholders need confidence ranges rather than false precision, and when understanding project risk is as important as knowing the target date.
Template Components
Estimate Worksheet
A table for capturing three estimates per activity (in days): Optimistic (O), Most Likely (M), and Pessimistic (P). The template includes pre-labelled rows for Activities A through G, plus columns for calculated Expected duration (TE), Standard Deviation (σ), and Dependencies. The formulas used are:
TE = (O + 4M + P) ÷ 6
σ = (P − O) ÷ 6
Time-Scaled Plan
A visual Gantt-style timeline spanning 11 weeks, divided into four swim lanes representing different workstreams. Each lane holds placeholder activity bars where you'll draw your tasks at their calculated TE length. One lane demonstrates "float"—the scheduling flexibility that exists for non-critical activities.
Summary Footer
Fields for your overall project metrics: Expected project duration, Project σ (calculated as √(sum of σ² for critical path activities)), and the Likely range (±2σ, representing ~95% confidence). Includes the crucial reminder: "Quote the range to stakeholders, not the single number—that is the whole point of estimating this way."
How to Fill It In
Gather three estimates for each activity from your team—never settle for just one number
Calculate TE and σ for every row using the provided formulas
Draw activity bars on the timeline at their TE length
Chain dependent activities—connect the bars that rely on each other; the longest chain determines your finish date
Key Benefits
Honest uncertainty: Communicates realistic ranges instead of over-confident single dates
Better decisions: Stakeholders understand risk and can plan accordingly
Team input: Captures the full spectrum of team knowledge through three estimates
Visual clarity: Timeline view makes dependencies and critical paths immediately visible
Cheers!
Khawaja Rizwan
