Early in my career I gave an executive a number I believed in. Fourteen weeks. I’d built it up from the task list, checked it with the team, added a margin that felt grown-up. It was the most honest number I could produce, and it was wrong by six weeks, and the six weeks were spent explaining the gap instead of closing it.
What I learned wasn’t to estimate better. Twenty years on, my raw first guesses aren’t dramatically better than they were. What I learned is that the estimate was never the problem. The contract we silently attached to it was.
An estimate is a probability wearing a number
When you say fourteen weeks, you mean something like “fourteen is the middle of a range that runs from eleven to twenty-two, assuming the API documentation is accurate and Priya doesn’t get pulled onto the outage.” What the room hears is fourteen. The range, the assumptions and Priya all vanish at the moment of transmission, and from then on you’re managed against the one version of the number you never actually said.
So give the range out loud. Give the assumptions in writing. A single number invites a commitment. A range invites a conversation about which end you’d rather fund, and that conversation is the entire point of estimating. It’s the same discipline as pricing scope at the moment of the yes, which I covered in the unpriced trade-off: the cost exists whether or not you name it.
Three habits that beat better maths
First, use history before judgement. Ask what similar work actually took last time, in this organisation, with these approval chains. The outside view is humbling and it’s usually right. Your gut remembers the coding. It forgets the six sign-offs.
Second, estimate in the unit you can defend. If the honest answer is “a quarter,” don’t say thirteen weeks. False precision reads as confidence and gets filed as commitment. Round numbers keep the uncertainty visible.
Third, re-estimate on purpose, at set points, and say so upfront. “This number is good enough to decide whether to start. We’ll know a real number after discovery.” That sentence, said early, buys you the right to update without it reading as failure. Said late, the same update reads as an excuse. Timing is the whole difference, a point I made about honesty under pressure in the problem with RAG reporting.
The real product
The value of estimating was never the number. It’s what producing the number forces you to discover: the dependency nobody mentioned, the assumption doing all the load-bearing work, the task that three people each thought someone else owned. The estimate is fiction. The estimating is intelligence. Keep the second, hold the first loosely, and never let anyone laminate it.
Ben Webb is an Australian project leader and speaker, AIPM Project Manager of the Year 2022 and IPMA World Project Manager of the Year nominee. He writes about delivery, leadership and events.
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