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Introduction to Estimation Questions

As a Product Manager, you'll need to make decisions based on incomplete information. You might need to quickly gauge market size for an opportunity or to do a gut-check on how many users might be interested in a feature. Estimation questions assess your ability to do this.

Estimation questions like “How many rental properties are listed on Airbnb in San Francisco?” can seem impossible at first. The key is realizing that interviewers don’t expect you to arrive at the exact answer. Instead, they’re interested in how you solve problems.

What to expect

Example questions include:

  • “How much money does the Google Play store make in a year?”
  • “Estimate the number of videos watched on YouTube per day.”
  • “What will the market size be for driverless cars in 2025?”

Most estimation questions can be answered using the same process though the information and intuitions you draw on to support your answers will change. You might see estimation questions that incorporate:

  • Strategic understanding: "What's the TAM of Slack?"
  • Technical knowledge: “How much does it cost to run YouTube for a day?”
  • Execution: “How much would it cost to capture Street View images for Manhattan?”

In this module, we’ll present a straightforward framework for approaching and answering estimation questions. We’ll show you how to reframe the problem, identify and break down key variables, and estimate unknowns using multiple methods.

What interviewers are looking for

Interviewers want to see you:

  • Make sense of the situation
  • Break down the problem
  • Make reasonable assumptions
  • Incorporate edge cases and discard unimportant factors
  • Manipulate numbers
  • Evaluate your answer in context

“Okay” vs. “good” vs. “great” answers

  • An okay answer provides a reasonable breakdown of the problem and makes large but reasonable assumptions for estimated values. Often the candidate may feel their final answer is off, but the assumptions are too broad to fully diagnose why that is.
  • A good answer breaks down the problem into its critical components. The problem is broken down enough that estimated values are well-justified. The candidate can reason about why their answer makes sense and can go back to examine how different assumptions would have changed their final answer.
  • A great answer provides a clear breakdown of the problem. It is thorough without needless complication, often incorporating the larger context and an understanding of the situation. Estimated values are well-justified, draw on deep understanding, and again are made with the larger context in mind. They feel tight, as if no other value would make sense given the assumptions. The candidate can discuss the meaning of their final answer in context, can comfortably entertain different assumptions, and assess how these would affect their answer.
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