Three-Point Estimation vs Planning Poker: Which Should You Use?
Both methods acknowledge that estimates are uncertain. They differ in how they handle that uncertainty and what they produce - both are covered, alongside the rest of the technique family, in the agile estimation techniques guide.
How three-point estimation works
Each estimator provides three values for each story:
- Optimistic (O): best case, everything goes right
- Most likely (M): what you'd expect normally
- Pessimistic (P): worst case, things go wrong
These combine into a weighted average: (O + 4M + P) / 6
This gives you an expected value with an implicit confidence range. It's particularly popular in traditional project management (PERT analysis) and works well when you need a probability-weighted number for scheduling.
How planning poker differs
Planning poker produces a single relative estimate (story points) through consensus. It doesn't try to model the uncertainty mathematically - instead, the discussion between high and low voters surfaces the uncertainty explicitly, and the team resolves it before committing.
When three-point wins
- You need to produce schedule estimates with confidence intervals
- You're estimating large pieces of work (epics, features) rather than user stories
- Stakeholders want to understand risk quantitatively, not just see a single number
When planning poker wins
- You're estimating at the story level for sprint planning
- You want the discussion that surfaces hidden complexity
- Your team is already calibrated on a relative scale
- Speed matters - three-point is slower per story
Can you combine them?
Yes. Some teams use three-point estimation for roadmap-level planning (quarters, big features) and planning poker for sprint-level work. The two operate at different granularities and serve different audiences.
Neither method removes estimation error. They give you different ways to understand and communicate the uncertainty.