T-Shirt Sizing

T-shirt sizing is an estimation approach that utilizes relative valuations. The estimation approach uses t-shirt sizes such as extra-small, small, medium, large, and extra-large. Similar to story points, the t-shirt sizing approach can differ from team to team and requires a common understanding of the estimated value selected. The strategy works best when a team has estimated previous stories or work items as a group, and the method can provide a measurement for large effort work items. The t-shirt sizing technique can produce an early estimate to give the business a metric of complexity for determining the level of effort. The early comparison allows stakeholders or requesters to determine if the effort required is worth the business value generated from the effort. The t-shirt size estimation technique offers a simple alternative to executing a more complex estimation process.

T-shirt sizing is an estimation technique used by Agile teams as a simple way to assess the size of a task or feature. The technique uses the sizes of T-shirts (S, M, L, XL, etc.) as a metaphor for the effort involved in implementing a user story or product backlog item. Each size corresponds to a relative level of effort, complexity, or time.

Here's a rough breakdown:

Small (S): A small task or feature is one that is straightforward for the team to complete. It's well understood, and there's little or no uncertainty or risk involved.
Medium (M): A medium task or feature is more complex. It requires more effort, may involve some uncertainty or risk, or might depend on other tasks.
Large (L): A large task or feature is one that will require substantial effort, may be complex or have high uncertainty, and has significant risks associated.
Extra Large (XL): This size could be for a task or feature that is so large or complex that it needs to be broken down into smaller parts before it can be estimated accurately.

T-shirt sizing can be a useful way to start the estimation process because it's simple and intuitive. It doesn't require the team to quantify the effort involved precisely, which can be difficult and time-consuming. Instead, it allows the team to make a quick, initial assessment and then get on with the work.

This technique is often used in the early stages of planning, where the team needs to make a rough estimate of the size of a large amount of work. Later on, as the work becomes better understood, the team might use a more precise estimation technique, such as story points.

It's important to remember that, like all estimation techniques, T-shirt sizing is not an exact science. The goal is not to produce exact estimates, but to help the team understand the work better, plan effectively, and have productive discussions about the tasks and features they're developing.