T-shirt sizing with Sprint Poker
The start card is set to the T-shirt deck, XS to XXL, and your new room comes with five sample roadmap items to size. Type your name, press Enter and share the link: everyone votes a size in secret, and the reveal shows the spread and who to ask when the team disagrees.
- Type your name and press Enter. The room is created with the T-shirt deck and the five sample items in its backlog; delete them or paste your own, one per line.
- Share the link or QR code. Up to 5 teammates join with a display name as voters in a free room; anyone else joins as a spectator to watch without voting.
- Agree what M means before the first vote: pick one item everyone knows and call it a Medium, so other items are sized relative to it.
- Everyone picks a size. Votes stay hidden until you press Reveal; the result shows how many sizes apart the votes are and names who voted lowest and highest.
- Ask the outliers to explain, re-vote if the discussion changed minds, set the final size and press N for the next item.
What to know
T-shirt sizes work where numbers create false precision: roadmap items, epics and anything sized before it has been broken into tickets. Arguing whether something is a 13 or a 21 implies an accuracy nobody has at that stage, while 'this is an L, about twice that M we did last quarter' is a judgement a team can make in a minute. The scale also reads well for people outside engineering, which makes it useful in planning meetings with product and design.
The scale only works if everyone shares an anchor. Before the first vote, name one finished piece of work as the reference Medium, and agree what XXL means for your team, usually 'too big to estimate, split it first'. Many teams also write down a rough duration band per size, such as S is a few days and L is most of a sprint, so a size can be compared with what actually happened later.
Hidden votes matter more with sizes than with numbers, because a single confident 'that's obviously small' anchors the whole room. Here the database rules keep each vote private until the facilitator reveals, so the spread you see is real. When the reveal shows S next to XL, the useful conversation is not the average but the assumption behind each card: one person knows about a migration, another assumes an existing component can be reused.
If you later need numbers for velocity or capacity, map sizes to points consistently instead of re-estimating, for example XS=1, S=2, M=3, L=5, XL=8, and keep XXL as 'split first'. Sprint Poker Pro's Calibration view compares estimates with real cycle time after the sprint, which shows whether your L items really take about twice as long as your M items, and when the scale needs re-anchoring.
Updated · Cosmovex
Questions
What sizes are in the T-shirt deck?
XS, S, M, L, XL and XXL, plus the usual ? and coffee cards for 'not sure' and 'need a break'. If your team uses a different set, Sprint Poker Pro lets the facilitator type a custom deck in the room settings.
When should we use T-shirt sizes instead of story points?
Use sizes for early, coarse estimates: roadmap items, epics, discovery work and backlog triage, where the team cannot yet break work into tasks. Switch to points or no estimates once items are small enough to finish within a sprint.
How do T-shirt sizes convert to story points?
There is no standard conversion, but teams commonly use XS=1, S=2, M=3, L=5, XL=8 and treat XXL as 'split it before estimating'. What matters is applying the same mapping every time so the numbers stay comparable.
How many people can join a sizing session?
A free room seats 5 voters plus any number of spectators, with unlimited rooms and rounds and no accounts. Stakeholders can follow as spectators. With Pro, the facilitator's rooms seat up to 1,000 voters.
Can I import our backlog instead of the sample items?
Yes. Paste items one per line in the backlog panel (free); issue keys like ABC-12 are detected and you can drag items into the order you want to size them. Dropping a Jira, Linear or GitHub CSV export is part of Pro.
The free plan covers everything on this page. Sprint Poker Pro ($29, paid once) is described on the Sprint Poker page.
