T-Shirt Sizing: The Executive Standard

The Cone of Uncertainty

At the start of a project, your estimation error margin is 400%. Trying to say "This will take 142 hours" is not science; it's a guess.

S/M/L/XL Logic

The human brain is terrible at absolute estimation ("14 hours") but excellent at Relative Sizing ("This rock is twice as heavy as that rock").

Size	Meaning	Timeline Proxy	Management Translation
S	"I know exactly how to do this."	Days	"Just do it."
M	"I need to look up a few things."	Weeks	"Put it in the roadmap."
L	"We need a design spike first."	Months	"We need budget approval."
XL	"This is a new product."	Quarters	"This is a strategic initiative."

The "No Estimates" Movement

T-Shirt sizing is the gateway drug to #NoEstimates. If you break all work down until it fits into a "Small", you stop needing to estimate. You just measure flow.

The Trap

Don't map Sizes to Hours. If you say "Small = 8 hours", you have just reinvented bad time-tracking. Keep it abstract. Keep it relative.