Planning poker and T-shirt sizing are related, but they are not exact opposites. Planning poker is a process for independently estimating and discussing work; T-shirt sizing is a scale using labels such as XS, S, M, L and XL. A team can use private cards with either numeric or size labels.
The practical choice is how much distinction your next decision needs. Use a coarse scale when rough comparisons are enough, and a more detailed discussion when assumptions need examination.
Compare the decision you need to make
These are practical tendencies, not restrictions. A team can run a thoughtful discussion using only a few labels, or use numeric cards too mechanically. The quality of the conversation matters more than the symbols.
| Question | Numeric planning poker | T-shirt sizing |
|---|---|---|
| Typical purpose | Discuss and estimate a manageable backlog item | Group work into broad relative sizes |
| Scale example | 1, 2, 3, 5, 8, 13 | XS, S, M, L, XL |
| Useful detail | Separating nearby reference stories | Distinguishing small, medium and large ideas |
| Main risk | Debating numbers more than assumptions | Leaving size labels too vague |
| Good next step | Record scope and an estimate, or split | Refine the most important groups |
When broad size labels help
Suppose a team is looking at twenty early product ideas. It may be enough to identify which ideas are obviously small, which depend on major changes and which are too unclear to size. T-shirt labels make that rough sorting possible without suggesting a precise forecast.
Choose examples for each label. “Medium” means little unless people know what a medium item looked like in their own work. If the team disagrees strongly, preserve that uncertainty rather than quietly putting the item in the middle group.
When a planning poker round helps
When an item is important enough to refine, private estimates can reveal details that a quick group classification missed. For instance, the team may agree that an email-invitation feature is medium, yet disagree on whether it includes permissions, reminder emails and an audit trail.
Use the reveal to compare those interpretations. Once the scope is clearer, the team can choose a numeric estimate or discover that the item should be split. Independent voting is useful because it gives each person a chance to think before hearing the most confident answer.
Do not treat size-to-point mappings as universal
There is no standard conversion in which M always equals 5 points or L always equals 13. A team can create a local working agreement, but it remains a convention tied to its references. Changing a label into a number does not add new information.
If an early large idea becomes several smaller stories, estimate the refined stories in their own context. Their combined points need not reproduce the first coarse guess exactly. The team has learned more about the work.
A simple way to choose
- Name the decision: early grouping, ordering a near-term item or deciding whether to split it.
- Choose a scale with only as much detail as that decision needs.
- Use familiar reference examples and let people estimate independently.
- Record the assumptions and uncertainty along with the result.
- Revisit the estimate when refinement changes the scope.
Sources and further reading
For the underlying methods and framework, start with these primary sources. Worked examples and suggested agendas above are illustrative.
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