T-Shirt Estimation
T-shirt sizing is a collaborative estimation technique that helps agile teams quickly categorize work items based on relative effort, using familiar clothing sizes (XS, S, M, L, XL) rather than precise time estimates. This automated template streamlines the process of sizing your backlog, providing clarity on scope and complexity without getting bogged down in detailed time estimates.
What Is T-Shirt Estimation?
T-shirt estimation is a relative sizing method where teams classify tasks using clothing sizes instead of specific time units. This approach acknowledges that estimating exact hours for tasks is often inaccurate, while comparative sizing is more reliable. It originated in agile development practices as teams sought more intuitive ways to discuss effort without committing to precise timeframes.
The clothing size metaphor makes the concept accessible:
- XS: Very small, straightforward tasks
- S: Small tasks requiring minimal effort
- M: Medium complexity tasks
- L: Larger, more complex tasks
- XL: Significant undertakings requiring substantial effort
- Too Big: Tasks that should be broken down further before implementation
Benefits & When to Use
T-shirt estimation is particularly valuable when:
- Planning upcoming sprints or releases
- Prioritizing features on a product roadmap
- Building a shared understanding of upcoming work
- Working with stakeholders who need general effort estimates without time commitments
- Onboarding new team members to the backlog
Teams benefit from:
- Quick decision-making around relative effort
- Reduced debate over precise hours or days
- Easier identification of items that need further breakdown
- Creating a common language for discussing work complexity
- Facilitating meaningful conversations about scope and requirements
How to Run a T-Shirt Estimation Session
Prepare Your Backlog (5 minutes)
- Import your items from Jira or CSV using the buttons at the top
- Add any missing items manually
- Arrange items in the "Ticket Funnel" zone, with higher priority items at the bottom right
Set Context (5-10 minutes)
- Explain the sizing categories to the team
- Optionally, provide examples of previously completed work in each size category
- Consider starting with the smallest items first to establish a baseline for comparison
Estimate Each Item (2-4 minutes per item)
- Move an item to the "Discussing" box
- Click "Focus View" to center the current item
- Explain the item and answer any clarifying questions
- Team members vote on size (XS, S, M, L, XL, or Too Big)
- Briefly discuss any significant differences in votes
- Click "Next" to assign the winning size and move the item to its lane
Review & Adjust (10 minutes)
- After all items are estimated, review the distribution across sizes
- Look for items that might be in the wrong category based on the overall patterns
- Pay special attention to "Too Big" items that need to be broken down
- Make final adjustments as needed
Export Results (2 minutes)
- Use the "Export" button to save your estimates
- Consider importing the data back into your project management tool
Total time: 30-90 minutes depending on the number of items and team size
Tips for a Successful T-Shirt Estimation Session
- Start with the smallest items to establish a baseline that makes comparative sizing easier
- Keep discussions focused on relative complexity, not implementation details or timelines
- Avoid overthinking the exact boundaries between sizes – the goal is rough categorization
- Watch for scope creep during discussions; note requirements questions but don't solve them now
- Be consistent with your sizing scale across sessions to maintain reliability
- Don't force consensus on every item; if there's sustained disagreement, note it and move on
- Review your estimates periodically to see if your team's sizing accuracy improves over time
Remember that the primary goal isn't perfect accuracy but rather creating a shared understanding of relative effort across your backlog to aid prioritization and planning decisions.
