The planning fallacy is the likelihood to underestimate the time it will take to finish a future task despite knowing that similar projects have taken longer in the past. For example, writers underestimate how long it will take to complete a novel; product managers miscalculate how long a new feature will take to build.
Studies show that we underestimate how long it will take even when we know we're likely to underestimate timelines.

The planning fallacy

<ul><li>Break projects down into smaller pieces and estimate how long each part will take.</li><li>Add 20% to your estimated completion time. It is better to plan for the unexpected than to be surprised by it.</li><li>Use historical data to make better predictions. Don't think you'll be able to finish faster next time.</li><li>Limit the scope of work. Instead of extending the timeline, reduce the scope of work.</li><li>Communicate early and often if you're going to miss a deadline.</li></ul>

Overcoming the planning fallacy

Our tendency to underestimate the time it will take to complete a future task despite knowing that similar tasks have taken longer in the past.

The planning fallacy

The Planning Fallacy

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