methodatlas
Method guideAgile

T-Shirt Sizing

A practical method guide: clarify prerequisites and materials, understand the complete process, and look up outputs, pitfalls, and stop criteria.

ComplexityLow
Time15-45 min
Participants2-12
FormatWorkshop + async
MaturityEstablished
Plan T-Shirt Sizing
01

Prerequisite

What needs to be finished first

Complete firstClear boundary

Set a comparable item set and included work; select XS–XL scale and stable reference items from the team's own experience.

Without a boundary, cases, periods, or variables become mixed.
Complete firstEvidence access

Comparable items, shared Definition of Done, XS/S/M/L/XL sizes, one reference item per size, and clarification pile

Missing sources remain visible as uncertainty.
02

Preparation

What needs to be ready before start

Materials

Comparable items, shared Definition of Done, XS/S/M/L/XL sizes, one reference item per size, and clarification pile

People / roles

Delivery team estimates · product owner clarifies · facilitator calibrates · experts answer questions

Pre-read

Set a comparable item set and included work; select XS–XL scale and stable reference items from the team's own experience.

Time needed

30–60 minutes for 10–25 comparable items; recalibrate when work mix changes.

Setup

Prepare a workspace with Scope · Anchors · Sort · Clarify · Close; separate example from live data.

03

Core question

The one question this method answers

Which rough relative size class describes each comparable item using shared anchors without false precision or hidden point conversion?

04

Flow

Phases with goal, actions, output and pitfall

T-shirt sizing places work into a small number of size classes and focuses on relative scale rather than fine-grained precision. It creates a quick shared reference for planning and discussion while details are still emerging.

T-Shirt Sizing · working structure

Fictional example

Fictional values show the actual method fields.

T-Shirt Sizing · working structure
ItemIncluded workComparison anchorFirst placementBoundary assumptionFinal sizeFollow-up
Delete tokenAdd evidence and rationale.Build, test, security, rolloutS · validate billing addressSExisting endpoint; no migration pathSReady
Save cardAdd evidence and rationale.Build, test, security review, rolloutM · save provider tokenM/LM without guest users and migration; otherwise LMFix scope in item
Card managementAdd evidence and rationale.List, default card, delete, failure pathsL · new payment methodLOne provider; no migrationLReady
Provider migrationAdd evidence and rationale.Auth, migration, fallback, certificationLarger than L anchorXLSeveral independent outcomesXLSplit into three items

  1. 1. Included work

    Delete token
    Build, test, security, rollout
    Save card
    Build, test, security review, rollout
    Card management
    List, default card, delete, failure paths
    Provider migration
    Auth, migration, fallback, certification

  2. 2. Comparison anchor

    Delete token
    S · validate billing address
    Save card
    M · save provider token
    Card management
    L · new payment method
    Provider migration
    Larger than L anchor

  3. 3. First placement

    Delete token
    S
    Save card
    M/L
    Card management
    L
    Provider migration
    XL

  4. 4. Boundary assumption

    Delete token
    Existing endpoint; no migration path
    Save card
    M without guest users and migration; otherwise L
    Card management
    One provider; no migration
    Provider migration
    Several independent outcomes

  5. 5. Final size

    Delete token
    S
    Save card
    M
    Card management
    L
    Provider migration
    XL

  6. 6. Follow-up

    Delete token
    Ready
    Save card
    Fix scope in item
    Card management
    Ready
    Provider migration
    Split into three items

All values are fictional.

Reference · original teaching example

  1. 1

    Scope

    Comparison frame

    Goal

    Comparison frame: Set item set, sizing dimension, and Definition of Done across all sizes.

    Inputs for this step

    • Set a comparable item set and included work; select XS–XL scale and stable reference items from the team's own experience.
    • Comparable items, shared Definition of Done, XS/S/M/L/XL sizes, one reference item per size, and clarification pile

    Actions

    • Set item set, sizing dimension, and Definition of Done across all sizes.

    Output

    Comparison frame

    Set item set, sizing dimension, and Definition of Done across all sizes.

    Quality check

    Are items comparable and does size include the same work types?

    Pitfall

    Features, research, and operations projects are sorted together. Split the item set or establish one shared sizing dimension.

    Timing: 5–10 minutes

  2. 2

    Anchors

    Size anchors

    Goal

    Size anchors: Choose one known item per size and explain the order through actual work.

    Inputs for this step

    • Comparison frame

    Actions

    • Choose one known item per size and explain the order through actual work.

    Output

    Size anchors

    Choose one known item per size and explain the order through actual work.

    Quality check

    Are anchors from the same context and clearly ordered?

    Pitfall

    Sizes are converted into days or points. Describe anchors as relative work and do not convert them numerically.

    Timing: 5–10 minutes

  3. 3

    Sort

    First sort

    Goal

    First sort: Place items silently relative to anchors; use XS/XL only for clear differences.

    Inputs for this step

    • Size anchors

    Actions

    • Place items silently relative to anchors; use XS/XL only for clear differences.

    Output

    First sort

    Place items silently relative to anchors; use XS/XL only for clear differences.

    Quality check

    Does every item sit between understandable neighbours?

    Pitfall

    The group debates every item before first placement. Place independently first; mark conflicts afterwards.

    Timing: 10–20 minutes

  4. 4

    Clarify

    Calibrated sizes

    Goal

    Calibrated sizes: Discuss boundary cases and different placements through scope, risk, and dependencies.

    Inputs for this step

    • First sort

    Actions

    • Discuss boundary cases and different placements through scope, risk, and dependencies.

    Output

    Calibrated sizes

    Discuss boundary cases and different placements through scope, risk, and dependencies.

    Quality check

    Was a size change explained by a different work model?

    Pitfall

    Majority vote hides different assumptions. The differing person explains first; then update scope or size together.

    Timing: 10–15 minutes

  5. 5

    Close

    Sizing view

    Goal

    Sizing view: Split or clarify oversized/unknown items; save sizes, anchors, and assumptions for later calibration.

    Inputs for this step

    • Calibrated sizes

    Actions

    • Split or clarify oversized/unknown items; save sizes, anchors, and assumptions for later calibration.

    Output

    Sizing view

    Split or clarify oversized/unknown items; save sizes, anchors, and assumptions for later calibration.

    Quality check

    Does every XL item have a split question and every unclear item an owner?

    Pitfall

    XL is accepted as a plannable work package. Split XL; place unknown work in clarification rather than forcing a size.

    Timing: 5–10 minutes

05

Artifact

What comes out at the end

Sketch: what the artifact looks like

T-Shirt Sizing · Rough Order of MagnitudeDeliberately sort items imprecisely from XS to XL, use references, and mark large items for slicing
T-Shirt SizingThe visual shows a T-shirt size axis from XS to XL, reference items, placed items, and a split candidate.Create an early size signal without false precisionItems are compared relatively; XL is not an exact value, but a signal for slicing, discovery, or clarification.relative size axisexplain scale firstcompare items relativelyflag large itemsXSsmallSmanageableMnormalLlargeXLneeds slicingStory AEpic BFeature CReference itemknown size for calibrationno hoursdeliberately rough, relative, and earlySplit candidateXL means clarify or slice
Form

Relatively ordered items in XS/S/M/L/XL with anchors, boundary assumptions, clarification pile, and split rule for oversized work.

Versioning / ownership

Record date, owner, source state, and review date; preserve prior versions.

Tool alternatives
  • XS–XL sizing lane
  • Reference items
  • Clarification and split pile

t-shirt-sizing-working-template.md

Set subject, evidence, roles, flow, and review.

T-Shirt Sizing: Worksheet

Question

To be confirmed

Desired outcome

To be confirmed

Scope

Practice run Time: 30–60 minutes for 10–25 comparable items; recalibrate when work mix changes.

Complete this worksheet on paper or in your own document during the work.

Preparation for this scope

Method setup

  • Materials: Comparable items, shared Definition of Done, XS/S/M/L/XL sizes, one reference item per size, and clarification pile
  • Roles: Delivery team estimates · product owner clarifies · facilitator calibrates · experts answer questions
  • Advance information: Set a comparable item set and included work; select XS–XL scale and stable reference items from the team's own experience.
  • Overall time needed: 30–60 minutes for 10–25 comparable items; recalibrate when work mix changes.
  • Setup: Prepare a workspace with Scope · Anchors · Sort · Clarify · Close; separate example from live data.

Prepare for the work steps

Scope: Comparison frame

  • Set a comparable item set and included work; select XS–XL scale and stable reference items from the team's own experience.
  • Comparable items, shared Definition of Done, XS/S/M/L/XL sizes, one reference item per size, and clarification pile

Anchors: Size anchors

  • Comparison frame

Sort: First sort

  • Size anchors

Clarify: Calibrated sizes

  • First sort

Close: Sizing view

  • Calibrated sizes

T-Shirt Sizing · working structure

ItemIncluded workComparison anchorFirst placementBoundary assumptionFinal sizeFollow-up
Delete token
Save card
Card management
Provider migration
  • Delete token: Add evidence and rationale.
  • Save card: Add evidence and rationale.
  • Card management: Add evidence and rationale.
  • Provider migration: Add evidence and rationale.

The blank worksheet contains prompts only.

Reference · original teaching example

Scope: Comparison frame

Expected artifact: Comparison frame

Set item set, sizing dimension, and Definition of Done across all sizes.

Entry:

...

  • Are items comparable and does size include the same work types?

Anchors: Size anchors

Expected artifact: Size anchors

Choose one known item per size and explain the order through actual work.

Entry:

...

  • Are anchors from the same context and clearly ordered?

Sort: First sort

Expected artifact: First sort

Place items silently relative to anchors; use XS/XL only for clear differences.

Entry:

...

  • Does every item sit between understandable neighbours?

Clarify: Calibrated sizes

Expected artifact: Calibrated sizes

Discuss boundary cases and different placements through scope, risk, and dependencies.

Entry:

...

  • Was a size change explained by a different work model?

Close: Sizing view

Expected artifact: Sizing view

Split or clarify oversized/unknown items; save sizes, anchors, and assumptions for later calibration.

Entry:

...

  • Does every XL item have a split question and every unclear item an owner?

Open questions and next steps

...

Method guide: https://methodatlas.meierhoff-systems.de/en/methods/t-shirt-sizing/run-sheet

06

Example output

Concrete filled scenario, fictional example

Fictional example for orientation. Counts and timings describe this case and are not universal requirements.

t-shirt-sizing-beispiel.md

Concrete filled scenario, fictional example

Fictional teaching example: T-Shirt Sizing · working structure

ItemIncluded workComparison anchorFirst placementBoundary assumptionFinal sizeFollow-up
Delete tokenBuild, test, security, rolloutS · validate billing addressSExisting endpoint; no migration pathSReady
Save cardBuild, test, security review, rolloutM · save provider tokenM/LM without guest users and migration; otherwise LMFix scope in item
Card managementList, default card, delete, failure pathsL · new payment methodLOne provider; no migrationLReady
Provider migrationAuth, migration, fallback, certificationLarger than L anchorXLSeveral independent outcomesXLSplit into three items
07

Pitfalls

Recognize symptoms and steer against them

Quick overview, the full text is in the matching phase in the flow

  1. Comparison frameFeatures, research, and operations projects are sorted together.View in phase
  2. Size anchorsSizes are converted into days or points.View in phase
  3. First sortThe group debates every item before first placement.View in phase
  4. Calibrated sizesMajority vote hides different assumptions.View in phase
  5. Sizing viewXL is accepted as a plannable work package.View in phase
08

Stop criteria

When to pause, resolve prerequisites, or choose another approach

Stop Scope: Are items comparable and does size include the same work types?
Stop Anchors: Are anchors from the same context and clearly ordered?
Stop Sort: Does every item sit between understandable neighbours?
Stop Clarify: Was a size change explained by a different work model?
Stop Close: Does every XL item have a split question and every unclear item an owner?

Method after Agile Community. The method emerged from, or was spread through, the agile community of practice. Curated with 1 sources.

Sources: T-Shirt Sizing

Flow, timeboxes, and pitfalls are editorially curated practice recommendations based on the listed sources.

Where to go next?

Story Splitting method illustration showing its working structure
Agile
Story Splitting

Breaks items flagged as oversized into smaller, estimable slices.

Paper illustration for Planning Poker.
Agile
Planning Poker

Later refines roughly sorted items with a more precise relative estimate.

View in playbookImprove Estimation and ForecastingMove from intuition to shared sizing, uncertainty, and delivery forecast.

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