All About T-Shirt Sizing Agile Estimation Technique

Companies using Agile find its one aspect really good and that it is not rigid. If the organizations using Agile get the essence of it, they can easily customize it to suit their needs to ensure maximum output. One of the best examples of this is Agile Estimation. The entire product is set through these estimation techniques and they make it easy for the team to get through the product.

Almost all the Agile teams do estimation and use different estimation techniques by breaking complicated products into smaller parts. In addition, when estimations are recorded, it is helpful in measuring the team's velocity and output and hence creating release plans in a better way. There are many Agile estimation techniques including affinity mapping, dot voting, story points, a bucket system, and t-shirt sizing. Each has its own benefits. In this article, let’s discuss t-shirt size estimation in Agile.

Why Teams Prefer T-Shirt Sizing Over Other Estimation Techniques?

Agile teams have several estimation techniques to choose from, but T-Shirt Sizing remains a favorite due to its simplicity and adaptability. Unlike numerical estimation methods like story points, which require assigning specific values, T-Shirt Sizing eliminates the pressure of accuracy in early-stage planning. Teams appreciate this approach because:

• It encourages quicker decision-making and helps teams get through estimation without getting caught up in excessive debates.
• It works well for high-level planning and helps stakeholders to understand effort distribution.
• It reduces cognitive load, as teams don’t have to worry about precise numerical values initially.
• It helps in task prioritization so teams can focus on the right User Stories without getting stuck in minor details.
• It is adaptable for agile teams to introduce custom labels or categories that make sense for their workflow.

By simplifying the estimation process, T-Shirt Sizing allows Agile teams to focus more on execution rather than getting bogged down by complex calculations.

What Is T-Shirt Sizing In Agile

T-Shirt size estimation in Agile is a technique that uses relative estimation. This estimation technique is helpful in planning effectively for a longer time. The T-Shirt sizing technique is a tool that helps in both product estimation and capacity planning. It helps you in knowing how much time or effort a particular initiative will take. Usually, Agile begins with either a high-level estimation of the product or a macro view of the product. This means the teams are able to arrive at a long-term plan for the product. And one of the most popular techniques used for this purpose is t-shirt sizing which estimates story points using relative estimation. It estimates what time, budget, and effort would be required for a particular product. The T-Shirt sizing Agile estimation technique is particularly beneficial for those teams that have just started using Agile and want a relative estimation for a product. On the basis of the way you use this technique, a t-shirt size can depict the scope of the product, the effort needed for it, the work hours required for it, the complexity of the product, time estimates, or all of these.

The t-shirt sizing technique is based on the concept of basketing meaning items with similar sizes are grouped together. Teams mutually collaborate, discuss, and then arrive at a decision on size. The size of a User Story is set by the team relative to others. The t-shirt size estimation in Agile starts at a t-shirt size in order to plan the future releases. This planning is then split into story points for the purpose of Sprint planning. And the story points can be further broken into hours for executing Sprint. Irrespective of this, the important point here is that as the work gets closer and closer to a developer's keyboard, more accurate estimation becomes easier and smaller. The t-shirt planning works very well for defining the product blueprint and Release Planning. 

How Does T-Shirt Sizing In Agile Work?

When you go to a store to buy a t-shirt for yourself, the t-shirts are marked XS, S, M, L, XL denoting extra small, small, medium, large, and extra-large sizes which means this is a relative sizing and they can fit different shoulder sizes. You can easily select what fits you. It becomes much easier to choose from such sizing than numerical sizing like 36, 38, 40, etc.

In the same way, different items or User Stories can be put in different categories like extra small, small, medium, large, or extra-large. In this way, numerical scores linked to story points are removed by the t-shirt size estimation technique. So, as far as the effort required for a story is concerned, this gives developers the leverage to be more flexible and dynamic.

Generally, a team uses the following process for t-shirt size estimation:

1. All the members of the team join the estimation session and are given the XS, S, M, L, and XL cards.

2. The team is given a brief explanation of the User Story for which the estimation is to be done by the Product Owner. After listening to the briefing, the team members ask questions to bring more clarity to their understanding of the User Story. Usually, the questions asked are like this:

• Is it required to learn any new thing for this User Story before the design stage is started?
• Is it possible to complete this story with the existing code class library or a new one is required to be written?
• Are any special measures required for unit testing for this story?
• What main user expectations are being targeted in this story?

3. After all these questions are answered, each member of the team assigns a t-shirt size to the story.

4. All members of the team then display their cards at the same time.

5. If every member has picked the same card, then it is taken as the final estimate. In case members have picked different cards, then the team holds a discussion until a consensus is reached on one size.

6. More User Stories are taken one by one and the team repeats the above process for each story till all the stories have been estimated.

7. The team can add another step to the above process if it wishes. It can estimate the time required to complete these stories after completing the estimation of all the stories.

So, you can see it is an easy and quick technique of relative sizing but the most important aspect of t-shirt size estimation is that the team should reach a consensus.

Common Challenges with T-Shirt Sizing and How to Overcome Them

While T-Shirt Sizing is simple, teams often face challenges when applying it in Agile workflows. Some common issues include:

• Lack of alignment on what each size means – One team may consider a ‘Large’ item too complex, while another may think it’s manageable. To avoid misalignment, teams should document their size definitions clearly.
• Difficulty in transitioning from rough estimates to execution – Because the technique focuses on relative sizing, teams might struggle to translate sizes into concrete timelines. The best way to bridge this gap is by introducing a mapping system that links sizes to historical velocity.
• Underestimation or overestimation due to missing details – If teams don’t discuss complexities thoroughly, they might end up with misleading estimates. Encouraging open discussion and refining estimates as more information becomes available can mitigate this risk.
• Resistance to change from teams used to numerical estimates – Some teams might be hesitant to move away from traditional numerical methods. To ease the transition, teams can experiment with hybrid models, combining T-Shirt Sizing with numerical techniques like story points.

When Should You Use T-Shirt Sizing?

T-Shirt Sizing isn’t suitable for all types of Agile estimation. However, it works best in the following scenarios:

• Early-stage planning – When teams need a rough estimate of effort without diving into details.
• Large product backlogs – Helps quickly categorize and prioritize tasks without getting overwhelmed.
• Cross-functional teams – Encourages discussions that lead to better alignment across different expertise areas.

• New Agile teams – Provides an easy entry point for teams unfamiliar with complex estimation techniques.

What To Do And What Not To Do

There are certain dos and don'ts for t-shirt size estimation which, if followed, give the best results. Let's have a look:

• You can think of bigger things and targets while doing t-shirt size estimation because your results will be rough estimates, So you can work freely.
• Do not unnecessarily increase the number of sizes as this technique is for simplifying decision-making for you so do not make the process complex by needlessly adding sizes.
• When working in and with a team, there are numerous ideas that come from all directions from every team member which may lead to a diversion from the goal. Make sure that you confine yourself to the scope of the estimation. You should not lose sight of the goal and make sure that the estimation is taking you nearer to the goal.
• It is not necessary to stick with t-shirt labels only. If you want, you can take other labels to denote sizes like fruits with the smallest fruit denoting the smallest size and the biggest fruit signifying the largest size. You can be innovative with the sizing labels. Idea is to reach a common agreement on size.

Pluses And Minuses Of T-Shirt Sizing Estimation

There are many pluses of the t-shirt size estimation technique but at the same time, there are a few minus points too. Let's see the pluses first:

• More number of User Stories can be estimated in less time as it is a simpler method
• It is very useful for the teams that are just starting in Agile 
• Teams can set their priorities in a better way and know the amount of effort they would be required to put with flexible deadlines
• Since the deadlines are flexible, in case there are impediments developers can reset the delivery time or their priorities
• The t-shirt size estimation works well when there are large backlogs

Now the minuses:

• In the t-shirt estimation technique, accuracy is compromised somewhat because the estimates achieved are on the basis of sizes rather than numerical values
• Estimation arrived at is relative
• At a later stage, if the team wants to calculate velocity, it may need to convert the sizes into numerical values

Overall, for getting preliminary estimates, the t-shirt size estimation is a very useful approach. All the stakeholders and team members get a projection of how much time and effort would be required for a particular product. As said earlier, it can be used when there is a large backlog or the team has just started working on the Agile framework. These teams which are new to the Agile framework can initially keep using the t-shirt size estimation technique and can later on move to more accurate techniques once they get a sufficient grasp of other more accurate estimation techniques. If the team is focused and follows the correct process, the t-shirt size estimation technique can increase its efficiency by giving faster and better estimates.

References

1. https://doasync.com/blog/what-is-t-shirt-sizing/
2. https://www.easyagile.com/blog/agile-estimation-techniques/