Comparison
Planning Poker vs T-Shirt Sizing: Which Should Your Scrum Team Use?
Both methods estimate the relative size of work. Both prevent hour-by-hour guessing. But they make different trade-offs, and the right choice depends on where you are in the sprint cycle and who's in the room.
How planning poker works
Planning poker uses a numbered card deck to estimate story complexity, most commonly the Fibonacci sequence (1, 2, 3, 5, 8, 13, 21, ?). Each participant votes privately, then all cards are revealed at the same time. The simultaneous reveal prevents anchoring: no one's estimate is influenced by what others said before they committed to a number.
When estimates diverge significantly, the highest and lowest voters explain their reasoning. This discussion surfaces hidden complexity or misunderstood scope. The team re-votes until they reach consensus, or agree to table the story for further refinement.
How T-shirt sizing works
T-shirt sizing uses a simple categorical scale, typically XS, S, M, L, XL, XXL, to give stories a rough relative size. It's faster than Fibonacci because there are fewer options to choose between, and the labels are intuitive to non-engineers: most people have an immediate sense of what "large" or "extra small" means in context.
The trade-off is resolution. You can't tell whether a story is a "13" or a "21" with T-shirt sizing: they might both end up as "XL." For backlog ordering that's fine; for sprint capacity planning it can create problems.
Side-by-side comparison
| Dimension | Planning Poker | T-Shirt Sizing |
|---|---|---|
| Scale | Fibonacci (1, 2, 3, 5, 8, 13, 21, ?) | XS, S, M, L, XL, XXL |
| Precision | High, fine-grained enough for sprint capacity planning | Low, fast categorisation rather than precise sizing |
| Speed | Slower, with discussion rounds and re-voting | Faster, with fewer choices and quicker consensus |
| Learning curve | Moderate, new team members need onboarding on story points | Low, labels are immediately intuitive |
| Best for | Sprint planning, items going into the next 1–2 sprints | Early backlog grooming, prioritisation workshops |
| Stakeholder inclusion | Engineers vote; stakeholders observe as spectators | Accessible to mixed audiences including non-technical stakeholders |
| Deck options | Fibonacci, modified Fibonacci, powers of two | XS–XXL (fixed scale) |
When to use planning poker
Planning poker is the right tool when:
- You're estimating stories that will go into the next one or two sprints. The higher resolution of Fibonacci numbers lets you fill sprint capacity accurately. A sprint where all your stories are "Large" is harder to plan than one where you have a mix of 3s, 5s, and 8s.
- Your team is already familiar with story points and has a stable velocity. The Fibonacci scale becomes meaningful once you have a reference point. Once the team knows what a 5 feels like, the whole scale calibrates around that anchor.
- You want to surface complexity and uncertainty through discussion. The structured rounds of planning poker are designed to generate conversation, not just produce numbers.
When to use T-shirt sizing
T-shirt sizing is the right tool when:
- You're doing early backlog grooming on a large number of stories. Moving quickly through 30–40 items to get a rough prioritisation is much faster with five categories than with a Fibonacci scale.
- Your audience includes non-technical stakeholders such as product managers, designers, or executives, who need to participate in sizing without a story-points background. "Is this Large or Extra Large?" is a more natural conversation than "Is this a 13 or a 21?"
- You're new to estimation and want to build the habit before introducing more nuance. T-shirt sizing is a good on-ramp to relative estimation for teams that have only ever estimated in hours.
Using both in the same workflow
Many mature Scrum teams use both methods at different stages of the same backlog lifecycle, and this combination is arguably the most effective approach overall.
T-shirt sizing for grooming
During quarterly or monthly backlog grooming sessions, use T-shirt sizing to triage a large volume of stories quickly. This gives the product owner a rough relative ordering and helps identify which items are ready to refine further and which need more work on the requirements.
Planning poker for sprint planning
When a story moves from "groomed" to "ready for the next sprint," run a planning poker round to get a precise Fibonacci estimate. At this point the story should be well-defined enough to estimate accurately, and the team needs a real story point value to plan sprint capacity.
The two methods complement each other cleanly: T-shirt sizing handles volume while planning poker handles precision. Using both avoids the common failure mode of either estimating too early (with insufficient information) or estimating too slowly (spending 10 minutes on every story in a 40-item backlog).
Try it with your team
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