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Agile estimation, unlocked: mastering t-shirt sizes in Jira

Estimating tasks in agile project management is essential, yet it's often as pleasant as poking yourself in the eye with a paper clip. Predicting the duration and complexity of a task is a challenging endeavour that agile teams continuously strive to simplify.

Jira typically offers numerical estimation methods, with story points being the most popular. However, numerical estimation has its drawbacks, leading many Jira users to seek alternatives.

Enter T-shirt size estimation in Jira.

What is T-shirt Size Estimation?

T-shirt size estimation is a straightforward and user-friendly agile estimation method, simpler than story points.

The concept involves assigning a T-shirt size—extra small (XS), small (S), medium (M), large (L), extra large (XL), or extra extra large (XXL)—to a task or user story based on the effort needed to complete it. This approach eliminates numerical estimation, although some teams do assign numerical values to T-shirt sizes, which somewhat defeats the purpose.

T-shirt Sizes vs. Story Points

Ron Jeffries, a co-creator of Extreme Programming, once expressed regret over story points, highlighting two key issues.

Firstly, story points often lead people to equate points with hours or days. If you explain estimation as "a point equals a day's work," you miss the point of agile estimation, which focuses on task size, not time. Additionally, this method assumes team velocity, or the number of points completed in a day, which should be determined by tracking averages over time.

Secondly, story points are overly precise, sparking debates about whether a task is worth 2 points versus 3, or 5 points versus 8, which can waste time and complicate estimation.

T-shirt sizing addresses these problems effectively.

With T-shirt sizes, estimation focuses on task size rather than duration. Unlike story points, T-shirt sizes don’t naturally translate into hours or days, reducing the risk of time-based thinking. Discussions about whether a task is an S or an M are more productive than debating 2 points versus 3. This method also simplifies the process, akin to choosing a medium T-shirt over deciding between sizes 38, 40, or 42.

Forecasting with T-shirt Sizes in Jira

Teams often rely on story points for forecasting because they equate points to velocity. Without points, how do you measure velocity and forecast milestones?

The solution is simple: count the number of Jira issues completed in a sprint. Since velocity is an average measured over time, counting completed issues can be as accurate as counting story points.

Pros and Cons of T-shirt Sizing in Jira

Here’s a look at the benefits and drawbacks of T-shirt size estimation in Jira to help determine if it’s suitable for your team.

Pros:

  • Visual estimation process, making it easier.

  • Quick consensus on estimates, beneficial for large item lists.

  • Focus on task size rather than time, implying a range instead of an absolute number.

  • Helps Jira newbies improve their estimation skills.

  • Avoids assumptions about team velocity.

Cons:

  • T-shirt sizes aren’t a standard Jira field; you need to create a custom field, which only allows for letter selections like XL, losing some visual benefits.

  • Inconsistent estimation can occur if team members interpret T-shirt sizes differently.

  • Some teams might convert T-shirt sizes to numerical values to calculate velocity, which defeats the purpose.

  • Even without explicit numbers, someone might start equating sizes to numbers (e.g., S = 10, M = 20).

Implementing T-shirt Sizing in Jira

To implement T-shirt size estimation in Jira, you need to create a custom field. This field will allow you to select from XS, S, M, L, XL, etc., for each issue. However, this basic setup lacks visual appeal.

To enhance the visual aspect, consider using the Jira app, Awesome Custom Fields. This app lets you display a graphic of an actual T-shirt in your Jira issues, allowing for colour and size customization. This visual representation makes the estimation process more intuitive and prevents the automatic association of sizes with specific numbers or times. Team members can quickly understand the task size at a glance.

01d92cfc-7f6d-4982-b14f-021d10538d28.png  394c3f3e-2f43-4bd1-9d35-56324933ad71.png

Awesome Custom Fields also extends these visual aids to Jira Service Management (JSM) users, allowing service teams to estimate change requests and other tasks effectively. Additionally, the app offers various agile estimation fields, such as price tags for cost estimation and weighted shortest job first (WSJF) fields for prioritizing tasks based on size and value.

Summary

If you aim for quicker, simpler, and more visual task estimation without the complications of numerical systems, T-shirt sizing is an excellent alternative to story points. While standard Jira requires a custom field for T-shirt sizes, the Awesome Custom Fields app provides a more visual and intuitive solution.

Enhance your Jira project management with visual aids and improved estimation by trying out Awesome Custom Fields. You can book a personal demo or try the app for free on the Atlassian Marketplace.

2 comments

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Paul Pasler
Marketplace Partner
Marketplace Partners provide apps and integrations available on the Atlassian Marketplace that extend the power of Atlassian products.
May 24, 2024

I personally prefer using T-shirt sizes because they are simple to use and easily understood by all participants, including those who are non-technical.

Which estimation method do you prefer? Hours, Story Points, T-shirt sizes,  no bulls*** estimation, or are you a NoEstimates advocate?

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Rustem Shiriiazdanov May 24, 2024

@Paul Pasler in my Team we are using Story Points. Funny thing is that we often forget Fibonacci sequence xD I think we could try T-shirt sizes, why not. They are easier to remember then just numbers.

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@Rustem Shiriiazdanov Yes we use T-Shirt sizes, and it helps me to prioritise the Backlog and in sprint planning! Definitely can recommend it!

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Rustem Shiriiazdanov May 27, 2024

@Kavitha Vaikunthavasan _Seibert-Media_ i have a question concerning the automation. Is it possible to create an automation that will fulfil SP in the ticket based on T-Shirt model? The reason is reporing: whereas it dull and boring to fill in SP into every ticket, I still would like to see numbers when i plan the sprint, and report against performance.

So it would be great if every time I select certain T-Shirt Sized value in ACF, the automation will put some value into issue story points.

@Rustem Shiriiazdanov That is a great approach to have the "best" of both worlds. Our custom fields can be used in automation, you can find the object structure in the documentation. You can try it and let us know how it works for your planning. 

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Alex G May 28, 2024

I wasn't familiar with the t-shirt estimation, thank you!

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