How to Use T-Shirt Sizing for Capacity Planning

You’ve got a great product idea, and your team’s excited. But then comes the key question: how much time, money, and resources will this actually take?

Most leaders jump straight into complex spreadsheets and hour-by-hour estimates. That’s a big mistake.You need a clearer perspective of the big-picture project scope before drowning in details. 

T-shirt sizing gives you that clarity fast by encouraging collaboration across your entire team. "T-shirt sizing helps teams estimate effort without overcommitting to exact hours, which encourages broader participation in planning,”  says Imran Salahuddin, Founder and CEO of Build Me App. “It’s a fast and intuitive way to get alignment across technical and non-technical stakeholders.” 

By generalizing the amount of resources and effort required to complete a project, you can help your team prioritize projects and organize sprints. This approach means you'll surface potential roadblocks and dependencies early. Learn more about how you can use T-shirt sizing to quickly scope upcoming projects. 

What Is T-Shirt Sizing?

T-shirt sizing is a project estimation technique that transforms abstract project complexity into something everyone understands: clothing sizes. Instead of arguing whether a feature takes 40 or 60 hours of development lead times, you classify it as small, medium, large, or extra large.

Each size represents a different level of effort and complexity:

• Small (S): Quick wins that one developer might knock out in a few days. It could be quick bug fixes, minor UI tweaks, or simple design changes. Examples of small projects include adding a filter to an existing report, updating your login page’s error messages, and adding a new field to a form.
• Medium (M): Features requiring a week or two of focused work from a small team. These might include integrating a new payment gateway, building a basic dashboard, or creating an automated email workflow. Medium projects often require coordination between the frontend and backend teams, but nothing that requires architectural changes.
• Large (L): Major feature changes demanding multiple sprints and cross-functional collaboration. For example, implementing a recommendation engine, redesigning your user onboarding flow, or building a mobile app from scratch. These projects touch multiple systems and need careful planning.
• Extra Large (XL): Strategic initiatives that reshape your product. We’re talking about complete platform migrations, launching in new markets with localization, or building an AI-powered analytics suite. Extra large projects often span quarters, not weeks.

T-shirt sizing shines brightest in Agile and Scrum environments where flexibility matters more than false precision.

Early-stage planning especially benefits from this simplicity. “For example, during the early planning of a logistics platform, we used T-shirt sizing to map out feature complexity for route optimization vs. real-time tracking," explains Oleksandr Andrieiev, CEO of Jelvix. "This helped us allocate the right team composition from the start without delaying the proposal phase." 

Particularly when you first begin scoping a project, this can help you determine how many people are needed to complete a sprint, what team members are needed, and roughly how long the project will take. Whether you're building a logistics platform or launching a new feature, T-shirt sizing lets you make critical resource decisions immediately instead of waiting weeks for detailed estimates.

Benefits of T-Shirt Sizing for Capacity Planning

T-shirt sizing isn’t just another project management fad. It solves real problems that plague technical teams and business leaders alike.

When you’re sketching out next quarter’s roadmap or evaluating a major initiative, this method cuts through complexity and gets everyone on the same page fast.

Simplicity

Complex estimation frameworks often create more confusion than clarity. You might have seen it happen: three-hour planning meetings where teams debate whether a task takes 13 or 21 story points. Meanwhile, your competitors ship features while you’re still planning.

T-shirt sizing strips away unnecessary precision during early planning stages. A streamlined approach makes communication between stakeholders easier.  "The simplicity and intuitive nature of T-shirt sizing helps us maintain agility during the planning phase while establishing realistic expectations for project timelines and resource allocation,” says Daniel Gorlovetsky, CEO of TLVTech. The result is faster decision-making by technical and non-technical stakeholders without sacrificing accuracy.

When you’re first proposing your project, a board usually doesn’t care if a feature takes 89 or 112 hours. They want to know: Is this a minor enhancement or a major investment? T-shirt sizing answers that question instantly. Then, with this information at hand, team leaders can spend more time digging into the requirements of the projects and begin allocating resources. 

Easy To Learn and Implement

New estimation methods usually require training sessions, documentation, and weeks of adjustment. Not T-shirt sizing. You can even implement it tomorrow morning.

Your newest product manager understands what “large” means just as well as your 20-year engineering veteran. No certification needed. No complex formulas to memorize. This universal understanding speeds up every planning conversation. This goes beyond your development team too: 

• Sales teams can participate meaningfully in roadmap discussions.
• Customer success can flag which requests are truly “small” versus those that sound simple but aren’t.
• Marketing understands why that “quick website update” might actually be a medium task involving backend changes.

T-shirt sizing is universal and is easy for all team members to understand. When cross-functional teams appreciate the scope and scale of a project, communication becomes stronger and collaboration becomes much easier. 

Encourages Collaboration

Traditional hour-based estimates often become territorial battles. Engineering says 200 hours. The product team thinks 100 sounds reasonable. And nobody wins these fights.

T-shirt sizing shifts the conversation from “how long” to “how complex.” This subtle change transforms the dynamics completely. "We find this relative approach helps our team quickly grasp the scope of work without getting bogged down in overly precise estimations, especially in the early stages of a project,” says Josh Webber, CEO of Big Red Jelly. “It fosters better communication and a shared understanding of the workload involved." 

When everyone understands the core agenda, planning meetings become more productive and decisions happen faster. Teams stop defending numbers and start discussing actual challenges, such as:

• What makes this feature large?
• Is it the technical complexity, the number of integrations, or the testing requirements?

These conversations surface risks and dependencies you’d miss in a spreadsheet.

Can Help Prioritization

Resource allocation becomes crystal clear when you visualize your roadmap in T-shirt sizes.

• Three large projects planned for Q2? That’s a red flag.
• A quarter full of small tasks? You’re probably not moving the needle on strategic goals.

This visual clarity helps you balance portfolios effectively. Mix quick wins (small tasks) that keep stakeholders happy with transformative initiatives (large/XL projects) that drive growth.

You can also spot capacity issues before they hit. If your team’s struggling with two medium tasks, adding a large project will break them. But a spreadsheet showing “847 total hours available” would obscure this reality.

Challenges of T-Shirt Sizing

T-shirt sizing works brilliantly for many scenarios, but it’s not a silver bullet. Understanding its limitations helps you apply it wisely and know when to switch to more detailed methods.

Not Very Precise

You can’t run payroll projections on T-shirt sizes. When the CFO needs budget estimates for next year’s initiatives, “mostly mediums and larges” doesn’t cut it.

T-shirt sizing works best during ideation and early planning. Once you’ve committed to a project and need detailed sprint planning, you’ll need actual time estimates. Think of it as your reconnaissance tool that’s great for surveying the landscape but insufficient for executing the mission.

Financial planning, contract negotiations, and fixed-bid projects all require more precision than T-shirt sizing provides. Use it to scope and prioritize, then drill down into specifics for execution.

Sizes Are Subjective

Your senior architect’s “small” might be a junior developer’s “large.” Without clear definitions and calibration, T-shirt sizing creates more confusion than clarity.

Team composition affects perception, too. A team with strong DevOps skills might rate infrastructure tasks smaller than a team that rarely touches deployment pipelines. Geographic distribution adds another layer. What’s medium in your San Francisco office might be large for your Paris team due to different tech stacks or processes.

Regular cross-team calibration sessions help in such scenarios, but they don’t eliminate subjectivity entirely. You’ll need examples, documentation, and ongoing discussions to keep everyone aligned.

Doesn’t Account for Changing Requirements

That medium feature you estimated last month? It’s now large after stakeholders added “just a few small requests.” T-shirt sizes don’t automatically adjust when the scope creeps in.

Market conditions shift, new regulations appear, and competitors launch features that force you to expand your original vision. Your T-shirt sizes become outdated quickly in dynamic environments.

This inflexibility can become problematic for long-running projects. A year-long initiative sized as large at kickoff might actually be extra large by month six. Without regular reassessment, your capacity planning falls apart.

How To Use T-Shirt Sizing

Implementation determines whether T-shirt sizing becomes a powerful planning tool or another abandoned process. Follow these T-shirt sizing capacity planning tips to make it work for your organization.

Align on Each Size

Start with clear definitions before sizing anything. Also, gather your technical leads, product managers, and key stakeholders for a calibration session.

For instance, you can create concrete examples from your actual work:

• Small: Adding Google Analytics to five landing pages
• Medium: Building single sign-on integration
• Large: Migrating from monolith to microservices architecture
• XL: Launching a complete mobile platform with offline capabilities

Always document these examples and also include typical team composition, rough duration ranges, and complexity indicators for each size. A small task might involve one developer for two to three days, touching a single system, with minimal testing overhead. An XL project could require multiple teams for six months or more, affecting core architecture, with extensive testing and migration planning.

Reference recent projects during sizing discussions. “Remember when we built the customer portal? That was large. This new vendor portal has similar complexity plus real-time inventory sync, so it’s probably XL.” This helps reinforce the sizes you’re working with and aligns team members’ expectations.

Assign T-Shirt Sizes to Each Initiative

Run sizing sessions with the right people in the room. Include architects who understand technical complexity, product owners who grasp business requirements, and team leads who know actual capacity.

Structure your sessions for efficiency:

• Present each initiative with clear scope boundaries.
• Allow clarifying questions, but avoid solution debates.
• Have participants size independently first.
• Discuss significant differences in estimates.
• Reach a consensus or flag items needing more investigation.

You also need to keep momentum during these sessions. If you’re stuck between medium and large for more than a designated time, pick large and move on. You can always refine later.

More importantly, avoid sizing too far into the future. Quarter-ahead planning works well. Annual roadmaps become fiction when you try to T-shirt size every feature for the next 12 months.

Track T-Shirt Sizes

Build a simple tracking system that everyone can access and understand. A shared spreadsheet works fine for smaller organizations. Larger teams might integrate T-shirt sizes into Jira, Azure DevOps, or similar tools.

Track both estimated and actual sizes. That medium integration that became large? Document why. Pattern recognition helps future estimation accuracy.

Create dashboards showing:

• Current sprint/quarter breakdown by size
• Historical accuracy (how often did our medium projections stay medium?)
• Team capacity trends (how many smalls equal one large for your team?)

But review these metrics quarterly. If 80% of your mediums become large, your definitions need adjustment. If certain project types consistently surprise you, dig deeper into why.

Gauge Workload

Transform your T-shirt sizes into capacity planning insights.

Start by establishing team baselines. Maybe your mobile team handles one large plus two mediums per quarter comfortably. Your backend team might crush three mediums but struggle with multiple smalls due to context switching.

Also, don’t forget to build a buffer in your planning. For instance:

• Never fill more than a certain percentage of the theoretical capacity.
• Account for maintenance, meetings, and unexpected work.
• Remember that team productivity drops when switching between many small tasks.

Keep in mind that you’ll have to regularly monitor team health indicators. Consistent overtime to complete medium tasks suggests you’re undersizing. Teams finishing large projects early might indicate conservative sizing or improved capabilities.

Also, remain flexible to adjust for team changes. For example, a new hire doesn’t immediately add small task capacity; they might actually reduce it temporarily while ramping up. Or senior engineers leaving might affect your large/XL capacity more than the small task throughput.

Using T-Shirt Sizing For Your Next Project

T-shirt sizing isn’t about perfect predictions. It’s about starting conversations, surfacing complexities, and making informed decisions before you’re too deep to change course.

You’ll find it most valuable during portfolio planning, early project scoping, and cross-functional alignment sessions. It breaks down barriers between technical and business teams while providing enough structure to make real decisions.

Follow these tips to get the most out of T-shirt sizing:

• Start small.
• Pick one team or project type.
• Define your sizes based on recent work.
• Run a few sizing sessions.
• Track results for a quarter.
• Then, expand what works and adjust what doesn’t.

The goal isn’t to replace all your planning processes. It’s to add a tool that brings clarity to complexity, speeds up decision-making, and gets everyone speaking the same language. In a world where development speed often determines market success, that common understanding might be your competitive advantage.

Your next strategic initiative doesn’t need perfect hour estimates on day one. It needs clear communication about scope, complexity, and resource requirements. T-shirt sizing delivers exactly that.

About the Author

Hannah Hicklen Content Marketing Manager at Clutch

Hannah Hicklen is a content marketing manager who focuses on creating newsworthy content around tech services, such as software and web development, AI, and cybersecurity. With a background in SEO and editorial content, she now specializes in creating multi-channel marketing strategies that drive engagement, build brand authority, and generate high-quality leads. Hannah leverages data-driven insights and industry trends to craft compelling narratives that resonate with technical and non-technical audiences alike. 

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