T-Shirt Sizing: lightweight estimation

Through my years working as an analyst and in project management, I have found T-shirt sizing has been the most efficient and effective method of estimating effort.

It is a relative estimation technique with roots in Agile project management, used to assess the effort or complexity of tasks. Inspired by universally known clothing sizes, instead of assigning numerical values, tasks are categorised into sizes like S, M, L, XL and then related to the information at hand and past experience of similar tasks.

This makes it easier to compare workload without getting lost in precise calculations. Although used in software development, it's extremely scalable, and also used in marketing, design and even operations. This makes it perfect for the D-I-S-E method.

Benefits of T-Shirt Sizing

• Simplicity & Intuition – Everyone understands clothing sizes, making it an accessible method for teams and individuals.

• Quick Estimation – A lightweight, flexible way to estimate work, helping gauge effort without deep analysis. This speeds up planning.

• Reduces Bias – Focused on relative effort rather than absolute time estimates, minimising unrealistic expectations.

• Supports Agile Planning – Helps balance workload effectively in sprint cycles, and is ideal for individuals building their own work plans.

Next step: The Eisenhower Matrix