Build it bottom up from the people who will do the work, then sanity check it top down against comparable past projects. Estimate ranges rather than single points, hold buffer at the project level instead of hidden inside each task, and write the assumptions down beside the date. Commit only once you know which assumptions have to hold for that date to survive.
Why interviewers ask this
Interviewers want to know whether your dates are engineered or wished for. Good answers include bottom up estimates from the doers, a top down reality check, ranges instead of false precision, and project level buffer rather than padding every task, which gets consumed regardless. They also listen for stated assumptions, because a committed date with no documented assumptions is a date you cannot defend when it moves.
How to structure your answer
- Estimate bottom up with the people doing the work.
- Cross check top down against a comparable project.
- Use ranges, not single point numbers.
- Hold buffer at project level where you can see it.
- List the assumptions the date depends on.
Example answer
I build bottom up from the people doing the work and then sanity check it top down against something comparable, because those two rarely agree and the gap is where the risk is hiding. I ask for ranges, best case and realistic, not a single number, because a single number is always a wish. Then the buffer goes at project level where I can see it and control it, rather than hidden inside every task, because padding inside a task gets spent whether it is needed or not. And I write the assumptions down next to the date: this assumes the test environment is available in week three, this assumes one reviewer and not two. When someone asks me to commit, I commit to the date plus that list, so when an assumption breaks we have a grown up conversation rather than an argument about whether I padded it.
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See how it worksFollow-up questions to expect
- What do you do when the sponsor has already announced a date?
- How do you estimate work the team has never done before?
- How much buffer is defensible before it looks like sandbagging?
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