Estimation question
How much storage data will YouTube need for the next year?
- Estimation
- Medium
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What this question tests
Whether you can build a bottom-up estimate combining upload volume, video length, and encoding assumptions.
How to approach it
- Clarify scope: net new storage needed for video uploaded to YouTube over the next year, accounting for multiple resolution copies.
- Estimate upload volume using a known reference point, hours of video uploaded per minute, and scale it to a yearly total.
- State a bitrate assumption per hour of standard and HD video to convert hours into gigabytes.
- Account for YouTube storing multiple encoded resolutions per video, which multiplies the raw storage need, and state that multiplier assumption.
- Multiply yearly upload hours by size per hour by the encoding multiplier to reach a total storage estimate.
- Present the result as a range in exabytes or petabytes, and flag the encoding multiplier as the most sensitive assumption.
What a strong answer includes
- Anchors the estimate to a known reference, hours uploaded per minute, rather than guessing total hours from scratch.
- Explicitly accounts for multiple resolution encodings per video, which most naive estimates miss entirely.
- States a labeled bitrate assumption, such as roughly 1 GB per hour of standard-definition video, before scaling up.
- Flags the encoding multiplier as the single most sensitive assumption driving the final order of magnitude.
Common mistakes
- Estimating storage for only one video resolution, ignoring that YouTube stores several encoded copies per upload.
- Presenting a suspiciously precise final number instead of a labeled, sanity-checked range.
Likely follow-up questions
- How would 4K and higher-resolution uploads change this estimate going forward?
- Which single assumption would most change your answer if it were off by 2x?
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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