Google·Product Manager·Onsite - Product Sense / Strategy·Intermediate

Intermediate

Apr 2026

Summary

Interviewed at Google, product or engineering adjacent role, got asked a classic estimation question about offline maps storage. Short post, not much context around the round or outcome.

Questions Asked (1)

How much storage space would offline maps require?

Product Sense & IdeationTechnical Trade-offsSystem Design

Author's notes

Classic back-of-the-envelope type question.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the scope: which offline maps product (e.g., Google Maps offline) and what level of detail (vector vs. raster, zoom levels, POIs). Then break down the storage calculation into components: base map tiles, road network, points of interest, and user-specific data, and estimate each based on typical data sizes and coverage area. Finally, provide a range and discuss trade-offs like compression, update frequency, and user expectations.

Pro tip: Show awareness that storage is not just about raw data size but also about update mechanisms and user perception—offline maps that consume too much space may deter downloads, so consider tiered options (e.g., basic vs. detailed) and automatic cleanup.

1. Clarify scope and assumptions

Define what 'offline maps' includes: geographic area (city, country, world), map detail (vector vs. raster, zoom levels), and additional data (traffic, POIs, satellite imagery). State assumptions explicitly.

2. Break down data components

List the main data types: base map tiles, road network vector data, points of interest, and user-generated data (e.g., saved places). Estimate the size of each per unit area.

3. Estimate sizes using benchmarks

Use known benchmarks: e.g., a vector tile for a city block is ~10-50 KB, road network for a country ~100 MB, POIs ~1 MB per 1000. Multiply by area and detail level.

4. Calculate total and provide range

Sum components for a typical area (e.g., a city, a country) and present a range (e.g., 100 MB to 2 GB) based on detail and coverage. Compare to device storage.

5. Discuss trade-offs and optimizations

Address compression, update frequency, selective downloading, and user control. Mention how Google Maps offline currently works and potential improvements.

Key Points to Mention

Vector vs. raster tiles: vector is more storage-efficient and scalable.
Zoom levels: higher zoom requires exponentially more tiles.
Coverage area: city vs. country vs. global; storage scales with area.
Additional data: POIs, traffic, satellite imagery add significant size.
Compression techniques: e.g., protobuf, gzip reduce storage.
Update frequency: frequent updates increase storage needs or require delta updates.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.