Agile estimation often feels broken. But maybe it’s not the technique. It’s the mindset behind it.
Ever been told, “You have to use story points”?
Or “That’s just how Agile works”?
What if the real problem isn’t the tool, but the thinking behind it?
“That’s how Agile works…”
Not long ago, a team told us their agile coach insisted:
“Everything must be estimated in T-shirt sizes.”
No explanation. No reason. Just a rule.
This isn’t rare. Teams are often told incorrectly:
- “You must use story points.”
- “Always estimate with T-shirt sizes.”
- “You don’t need to estimate at all.”
But here’s the truth:
- Agile doesn’t require story points
- Scrum doesn’t prescribe how to estimate
- And there’s no one right way to do it
You can estimate in:
- Story points
- Hours
- T-shirt sizes
- Relative sizing
- Or skip it entirely
The method a team uses often depends on their environment and experience.
Some approaches support better conversations than others. For example, relative sizing should help teams focus on complexity and uncertainty. But that only happens when it is used to explore, not to control.
Estimating in hours often leads to pressure, false accuracy and a focus on output instead of value.
It can also lead to Parkinson’s Law. Work expands to fill the time available, which makes teams slower without improving outcomes.
What matters most is the mindset. Estimation should support conversation and shared understanding. It can help teams make decisions and set expectations, as long as we remember that every estimate is a forecast, not a commitment.
Estimation isn’t about being right. It’s about learning and making better decisions.
Estimation should spark conversations, not control people
Too often, estimation turns into a game of fake certainty.
What we should be asking is:
- What’s the need?
- What’s the value?
- Is this small enough to deliver quickly?
- What might go wrong?
Estimation should invite collaboration, not silent commitment. And it should help us check whether something is valuable. Not just how much effort it takes.
Estimating with a pack of cards
We use a simple experiment in workshops.
Setup:
- Teams of 5
- Each gets a deck of cards
- We secretly remove one card
- They estimate how long it’ll take to find the missing one
They guess. We time it. Record it. Repeat.
What happens?
At first, they’re way off. Then they improve. But they’re never exact.
Even with a simple task, the uncertainty doesn’t disappear. And that’s the lesson.
The Cone of Uncertainty with a twist
Imagine meeting someone:
- At the local shop by 10am? You might leave 5 minutes early
- At head office in another city? 30 minutes buffer
- In another country? You go the night before
More complexity means more variability.
That’s the Cone of Uncertainty.
The earlier you estimate, the wider the range. Over time, your guesses improve. But they’re still guesses.
Even flow-based tools like Monte Carlo simulation work in probabilities, not promises.
Forecasting isn’t about being right. It’s about being transparent.
Should you stop estimating?
Not necessarily. But stop pretending estimates are facts.
What helps:
- Experience shrinks the range
- Data improves the odds
- Conversation creates alignment
Whether you use story points, T-shirt sizes, or nothing at all, make sure your estimates help your team think.
Bring this mindset to your team
The card experiment shows how uncertain even simple tasks can be. It’s a reminder that estimates aren’t about control. They’re about conversation and learning.
If you want to go deeper, consider asking your team:
- Are we trying to be accurate, or are we trying to understand?
- Do our estimates reflect uncertainty, or just effort?
- Are we using estimation to improve outcomes, or just track delivery?
We explore these questions further in our training and tools:
- Professional Scrum Product Owner – Shift from output to outcomes
- Applying Professional Scrum – Rethink planning, forecasting, and decision-making
- Tech Debt Simulator – See how poor technical practices make even great estimates meaningless
One last thought
Estimation isn’t about answers. It’s about better conversations.
And maybe the next conversation your team has about estimation is the one that finally makes it useful again.
Coming soon:
- Velocity. It’s Not What You Think It Is
- Velocity and the Cone of Uncertainty. Together at Last?
- Maybe Your Story Points Are Pointless?