Estimation question
Estimate the compute cost of giving every X user free access to Grok.
- xAI
- Estimation
- Hard
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What this question tests
Estimation combining a massive user base with realistic engagement assumptions to avoid wild overestimation.
How to approach it
- State assumptions: assume X has roughly 250 million monthly active users, but only a fraction would actively use a free Grok feature regularly.
- Estimate active Grok users: assume 10 percent of monthly actives try it in a given month, and of those, 30 percent use it weekly, giving roughly 7.5 million weekly active Grok users.
- Estimate queries per user: assume an average of 3 queries per weekly active user per week.
- Estimate cost per query: assume a blended inference cost of roughly 0.01 dollars per query for a mixed-size model serving free users.
- Multiply: 7.5 million users times 3 queries times an assumed 0.01 dollars equals roughly 225,000 dollars per week, or roughly 32,000 dollars per day, clearly marked as a rough estimate.
What a strong answer includes
- Builds from a realistic adoption funnel, monthly actives down to weekly active Grok users, rather than assuming all 250 million users query it constantly.
- States the per-query cost assumption explicitly and notes it would rise sharply if usage skewed toward longer, more complex queries.
- Shows clean arithmetic to a final daily or weekly cost figure, explicitly labeled as an order-of-magnitude estimate.
- Notes the result is highly sensitive to the adoption-rate assumption, and flags that as the biggest uncertainty in the whole estimate.
Common mistakes
- Assuming all 250 million monthly active X users query Grok daily, which wildly overstates realistic free-feature adoption.
- Skipping the cost-per-query assumption and jumping straight to a headline number without showing the reasoning.
Likely follow-up questions
- How would this estimate change if Grok became the default response to every X search query?
- What is the biggest cost lever xAI could pull to make free access sustainable at scale?
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More questions from xAI
Learn the skill behind it
Chapters of the AI PM course that teach what this question tests.
- Chapter 2: Data fluency: SQL, logs, and reading the truth yourself
- Chapter 9: Prove it paid off: outcomes, economics, and pricing
- Chapter 14: Get the job: the AI PM interview loop