⏱️ Estimation Techniques

Approaches to estimating effort, duration, and complexity.

Why estimation matters

Sets realistic expectations with stakeholders
Helps prioritize and plan sprints
Identifies tasks that need further breakdown
Tracks team velocity over time

Techniques

T-shirt sizing

Quick relative sizing: XS, S, M, L, XL Good for early-stage backlog grooming.

Story points (Fibonacci)

1, 2, 3, 5, 8, 13, 21 Measures complexity + effort + uncertainty, not hours.

Planning poker

Each team member picks a card (story point)
All reveal simultaneously
Discuss outliers
Re-vote until consensus

Three-point estimation

E = (Optimistic + 4×Most Likely + Pessimistic) / 6

Accounts for uncertainty with a weighted average.

Reference-based estimation

Compare new tasks to previously completed, known-size tasks.

Common mistakes

Converting story points to hours
Not accounting for testing, review, and deployment
Anchoring on the first estimate given
Estimating alone instead of as a team
Not updating estimates as new information emerges

Improving estimates over time

Track actual vs estimated effort per sprint
Calculate velocity trends (3-sprint rolling average)
Hold estimation reviews during retrospectives
Accept that estimates are ranges, not commitments