Fermi Estimate: Wine Bottles Uncorked on an Average Day
Company: Google
Role: Product Manager
Category: Product / Decision Making
Difficulty: medium
Interview Round: Other
Estimate the number of wine bottles that get opened on an average day.
```hint Pick a scope you can check
Settle where and what you are counting first, and plan one independent way to check your number before you start multiplying.
```
### Clarifying Questions
- Should the estimate cover one country, such as the United States, or the whole world?
- Do bottles opened in restaurants and bars count, or only those opened at home?
- What counts as a bottle: only standard 750 ml glass bottles, or also boxes, cans and large formats converted to bottle equivalents?
- Do you want an average day, or a particular day such as a Saturday or a holiday?
### What a Strong Answer Covers
- A scope agreed before any numbers: geography, home versus restaurant, and what a bottle is
- An equation that splits drinkers into groups with very different habits
- Round, clearly labeled assumptions and arithmetic the interviewer can follow aloud
- A sanity check from an independent angle, such as wine volume per adult per year
- Which assumption the answer is most sensitive to, and how weekends and holidays shift it
### Follow-up Questions
- How would the number differ on New Year's Eve compared with a typical Tuesday?
- If a startup sold a device that keeps an opened bottle fresh, how would you turn this estimate into a market size?
- Which assumption would you research first to tighten the estimate, and where would you find data on it?
Overview: A Fermi estimation question that asks how many bottles of wine are opened on an average day. It tests agreeing on scope first, building a clear equation from drinking habits, using round labeled assumptions, doing the arithmetic aloud, and sanity-checking the result from another angle.