Thinking, Fast and Slow · Daniel Kahneman

The planning fallacy examples

Curated by · reviewed 2026-06-01

The planning fallacy is systematically underestimating how long tasks will take and how much they'll cost — even after the exact same thing burned you before. Examples:

What is the planning fallacy? Read the full idea →

5 examples of the planning fallacy

  1. 'It'll take a weekend' renovations

    ...that quietly run for months.

  2. Software ship dates

    Teams confidently set a date, then miss it by half again — every release.

  3. The 20-minute errand

    ...that somehow swallows your whole morning.

  4. Big public projects

    Bridges, stadiums, and railways routinely land years late and billions over budget.

  5. 'I'll start early'

    The essay, the taxes, the report — begun late and finished at the deadline, despite last year's identical scramble.

How to spot it in yourself

You'll forget most of this by next week.

That's just how memory works. Lock the planning fallacy in with a 5-minute active-recall session — spaced repetition, no signup.

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