Opinion Piece: T-Shirt Sizing in Scrum - the Key to Agile Success in Financial Services?

As we belt towards the close of 2024, you’d think that the financial services industry — home to some of the most innovative fintech companies — would have agile delivery methods like Scrum down to a science. Yet, despite all the advancements in technology and the long-standing presence of agile methodologies, many businesses still seem to struggle with one deceptively simple concept: T-shirt sizing.

Is it a tech issue?

A product management issue?

Or does the problem lie at the business level?

But first...

What is T-Shirt Sizing?

For those unfamiliar with the term, T-shirt sizing is a quick and easy way to estimate the complexity, effort, or uncertainty of a task. Instead of trying to nail down the exact number of hours or resources required to complete a task, teams assign a rough size: small, medium, large, or extra-large.

It's an intentionally vague estimation technique designed to prioritise speed and collaboration over precision. And that, it turns out, is exactly what makes it so valuable in today’s fast-paced financial services environment.

Is This a Tech Problem?

At first glance, you might think this is a tech problem. After all, fintech organisations are brimming with engineers and developers who are used to hard metrics—hours logged, lines of code written, bugs squashed. To these tech teams, T-shirt sizing can seem frustratingly imprecise. It doesn’t give you the neat, clean numbers that traditional metrics provide, and for some, that lack of clarity is unsettling.

But this isn't where the real problem lies. Over the years, developers have become well-versed in agile frameworks and recognise that methods like T-shirt sizing are less about giving exact timelines and more about facilitating quick decisions. In most cases, they’ve adapted, even if they occasionally grumble about the ambiguity.

So, while there might be some friction between tech teams and the method, the core of the problem is more than just a technical one.

Is This a Product Problem?

Some argue that the struggle with T-shirt sizing stems from product management teams often finding themselves wedged between stakeholders who demand hard numbers and the inherently flexible nature of agile. Product owners and managers are expected to deliver specific deadlines, measurable ROI, and predictable costs. The very nature of T-shirt sizing, with its focus on rough estimates, doesn’t sit well with those who are used to the certainty of traditional project management methods.

That said, experienced product managers know how to thrive in agile environments. They can leverage T-shirt sizing as a way to communicate effectively with stakeholders, helping them understand that flexibility is the key to delivering a high-quality product.

The real issue may be less about product teams themselves and more about how the business structures its approach to agile. Without a company-wide shift in mindset, product managers will always feel the squeeze between stakeholder expectations and agile realities.

Is This a Business Problem?

This leads us to the crux of the issue: businesses themselves. I believe that the biggest challenge with T-shirt sizing, and agile estimation in general, often boils down to how well the entire organisation has embraced agile principles.

Financial services, in particular the TradFi elements, tend to hold on to ‘usual’ ways of doing business, where rigid forecasts and exact deadlines are the norm. In this environment, T-shirt sizing can seem too imprecise, too “soft.” Business leaders may struggle to trust a method that doesn’t offer exact figures, leading to misalignment between agile teams and executive expectations.

For T-shirt sizing to work effectively, businesses must recognise that it’s not about providing an exact estimate—it’s about helping teams move quickly, make decisions, and adapt to change. This requires a fundamental shift in how the organisation thinks about delivery: moving away from the illusion of precision and embracing the adaptability and speed that agile offers.

The Value of T-Shirt Sizing

So, why does T-shirt sizing still matter in 2024? Because it’s one of the simplest, yet most effective tools for managing uncertainty in fast-paced industries like fintech looking for fast-paced, value-add outcomes.

Here’s why T-shirt sizing is so valuable:

1. Relative Estimation – T-shirt sizing provides a quick, relative sense of how tasks compare in complexity and effort, allowing teams to prioritise without the need for exact data.
2. Simplicity and Speed – By avoiding time-consuming detailed estimates, teams can make quick decisions and keep projects moving—vital in a rapidly evolving sector like financial services.
3. Facilitating Conversations – T-shirt sizing fosters collaboration between developers, product managers, and stakeholders. When a task is labelled "extra-large," it prompts important discussions about whether it can be broken down into smaller parts.
4. Flexibility for Iterative Development – Financial services often require ongoing adaptation to changes in regulations, market conditions, or customer needs. T-shirt sizing supports the iterative nature of agile by allowing teams to adjust estimates as they go.
5. Reducing Anxiety About Precision – Fintech stakeholders often demand precise numbers, but T-shirt sizing removes the stress of being overly specific. Instead, it allows everyone to focus on progress, not perfection.
6. Capacity Planning – For teams juggling multiple projects, T-shirt sizing helps with capacity planning, giving a sense of how many "small" or "large" tasks can realistically fit into a sprint.
7. Common Language Across Teams – In cross-functional teams involving regulatory, security, and technical specialists, T-shirt sizing provides a simple, common language to estimate effort without getting bogged down in technical details.

Conclusion

T-shirt sizing is SO MUCH MORE than just an estimation tool!

It’s a significant litmus test for how well your organisation has embraced agile principles. For businesses, especially in financial services, the key to successful tech delivery isn’t about finding perfect estimates. It’s about fostering an environment where flexibility, collaboration, and speed take precedence (note: always within a risk-appropriate framework!)

If your company can embrace the ambiguity of T-shirt sizing, you’re well on your way to agile success. If not, you may find yourself clinging to outdated methods while your competitors race ahead, fuelled by the adaptability that agile offers.

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