Estimation question
Estimate how much budget is required for Facebook to maintain Facebook Photos.
- Meta
- Estimation
- Hard
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What this question tests
Estimation with infrastructure cost reasoning: can you break storage/infra spend into volume, cost-per-unit, and redundancy factors rather than guessing a dollar figure.
How to approach it
- Estimate photo upload volume: Facebook has a large user base, assume a fraction (e.g. 1-2 billion) upload photos regularly at an average rate per user per month (state as assumption).
- Estimate storage per photo, including multiple resolutions/thumbnails typically stored per original upload.
- Multiply to get total incremental storage added per month, then convert to a cost using an assumed per-GB storage cost at Meta's infrastructure scale (much lower than public cloud retail pricing).
- Add redundancy/backup factors, since photos are typically stored with multiple copies across data centers for reliability.
- Add operational costs beyond raw storage: bandwidth for serving images, CDN costs, and engineering/ops headcount maintaining the system.
- Sum the components into a rough annual budget figure, clearly labeling every assumption used.
What a strong answer includes
- Breaks the estimate into distinct cost components, storage, redundancy, bandwidth, and ops, rather than a single guessed number.
- Uses an infrastructure-scale cost-per-GB assumption (lower than public retail cloud pricing), showing awareness that a hyperscaler has different unit economics.
- Accounts for multiple stored resolutions per photo, a realistic detail most candidates miss.
- Presents a final range with assumptions clearly labeled rather than false precision.
Common mistakes
- Using public cloud storage retail pricing instead of infrastructure-scale unit costs.
- Forgetting redundancy/backup copies and bandwidth costs, and only estimating raw storage.
Likely follow-up questions
- How would this budget change if Meta reduced default photo resolution or added more aggressive compression?
- What's the single biggest cost driver in your estimate?
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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