Interview Questions › Guesstimate

Estimate monthly mobile data consumption in a country

Estimate the total mobile data consumed per month across an entire country like India (Pop: 1.4B) or the US (Pop: 335M) in Exabytes (EB).

Context

4G/5G mobile data has exploded driven by short-form video streaming, OTT platforms, social media, and gaming.

Clarifying questions to ask first

• Are we sizing India (1.4B pop)? (Yes)
• Does this include home Wi-Fi broadband or strictly cellular 4G/5G mobile tower data? (Cellular mobile data only).

How to approach it

1. Estimate Mobile Broadband Smartphone Subscribers (~850M in India / ~280M in US)
2. Estimate Average Monthly Data Consumption per Smartphone User (GB/month)
3. Multiply (Subscribers × Avg GB/Month) and convert Petabytes/Exabytes (1,000,000 GB = 1 PB; 1,000 PB = 1 EB)
4. Analyze data consumption by application: Video Streaming (70%), Social Media (15%), Gaming/Browsing (15%)

Framework: Total Monthly Mobile Data (EB) = (Active Smartphone Data Users × Average GB / User / Month) / 1,000,000,000

Sample answer

• Total mobile broadband users in India: ~850 Million smartphone users
• Average data consumption per user: ~24 GB / month (world-leading due to cheap data)
• Total monthly data = 850M users × 24 GB = 20.4 Billion GB = 20,400 Petabytes = ~20.4 Exabytes (EB) / month

1. Step 1: 850M smartphone SIMs
2. Step 2: 24 GB/user/month = 20.4 Billion GB
3. Step 3: Convert 20.4B GB = ~20.4 Exabytes/month (Jio handles ~12 EB, Airtel ~8 EB, Vi ~2 EB)

Executive estimate: ~20 to 22 Exabytes (EB) of cellular mobile data consumed monthly in India (~24 GB/user across ~850M smartphone subscribers).

What interviewers look for

• Smartphone Subscriber Base
• Per-User GB/Month Standard (~20-25 GB/mo in India)
• Unit Conversion (GB to Exabytes)
• Sanity Check against Telecom Regulatory Filings (TRAI/FCC)