⚡ Free Interview Prep Utility
System Design
Capacity Estimation Calculator
Never get stuck on mental math during FAANG interviews. Calculate Read/Write QPS, 5-Year Storage, Cache RAM, and Network Bandwidth with live formulas.
Input Parameters
Daily Active Users (DAU)10,000,000
Reads per user / day10
Writes per user / day1
Avg Payload Size (KB)50 KB
Cache Retention %20% (80/20)
Peak Traffic Multiplier3x Peak
Calculated Architecture Metrics
Write Throughput
116 QPS (avg)
348 QPS (peak 3x)
Formula: (10,000,000 × 1) / 86,400s
Read Throughput
1,157 QPS (avg)
3,471 QPS (peak 3x)
Formula: (10,000,000 × 10) / 86,400s
Storage Footprint
849.83 TB (5 Years)
476.8 GB / day
Assumes raw data without index/WAL overhead
Cache RAM (80/20 Rule)
953.7 GB
Caches 20% of 24h reads
Saves ~80% of DB hits using Redis/Memcached
Network Bandwidth
462.8 Mbps Egress
46.4 Mbps Ingress
QPS × Payload Size (in bits/sec)
Recommended DB Shards
425 Shards / Nodes
At 2 TB storage per PostgreSQL instance
Prevents large B-tree index degradation
Ready to architect this scale?
Open the interactive canvas to design the API Gateway, caching tier, and database topology for these capacity targets.