Estimating Storage Requirements for Offline Maps: A Guide for FAANG Interviews

This blog post is designed to help aspiring product managers prepare for FAANG interviews by providing a detailed guide on estimating storage requirements for offline maps. This is a critical consideration for services offering maps and navigation functionalities, and demonstrating your ability to solve this problem effectively can be a significant advantage.

Picking the Right Framework

For this specific problem, the Fermi Estimation framework is an ideal choice. This approach breaks down complex problems into smaller, more manageable pieces, allowing you to make reasonable assumptions and calculations based on available data.

Applying the Fermi Estimation Framework

Here’s a step-by-step guide on how to apply the Fermi Estimation framework to estimate storage requirements for offline maps:

1. Define the problem and decompose it

Determine the level of detail the offline maps will provide and the geographic scope they will cover.

2. Gather known data

Research average sizes of maps at different zoom levels and storage space required per unit of area.

3. Make assumptions

If specific data isn’t available, make logical assumptions. For example, you might assume a standard map with medium resolution for typical city navigation.

4. Estimate and calculate

Use your assumptions and known data to estimate storage requirements for a small area and scale it up to the required size.

Example

Let’s assume that a medium detail map of 1 square kilometer requires 2MB of storage space. If a user wants to download a map of New York City, which is roughly 780 square kilometers, the app would need approximately 1.56GB of storage. Adjustments and considerations for map detail, potential compression, and other factors affecting size can then be applied.

Tips for Effective Communication

• Clearly state your assumptions and justify them.
• Progress logically from one step of the estimation to the next.
• Convey understanding that the estimate is a rough approximation.
• Use simple math that can be easily followed by interviewers.

Conclusion

Estimating storage for offline maps is an example of how product managers are expected to think on their feet and provide reasonable data-backed answers. The use of the Fermi Estimation framework can guide you through this type of problem, allowing you to demonstrate methodical thinking and the necessary estimation skill set. Remember to practice these frameworks, as they are powerful tools to help you structure your thoughts and communications during your interviews.