System design interview essentials with back-of-the-envelope calculators, reference cards, and quick lookup tools.
Calculate storage requirements for system design - users, data size, retention, replication
Convert daily/monthly active users to requests per second (RPS/QPS)
Calculate bandwidth requirements for file transfers and streaming
Calculate transfer times, bandwidth usage, and cloud egress costs
Interactive reference for L1/L2 cache, RAM, SSD, network latencies
Quick reference for powers of 2 with byte conversions (2^10 to 2^50)
Calculate uptime/downtime for different availability levels (99.9% to 99.999%)
HDD vs SSD vs NVMe performance - IOPS, latency, throughput comparison
Convert between time units from nanoseconds to years
Convert between bytes, KB, MB, GB, TB, PB with binary/decimal modes
Convert between RPS, RPM, RPH, RPD with peak traffic calculations
CPU cache levels, RAM, and storage latency reference with optimization tips
Global network latencies, cloud regions, and distance-based calculations
Compare database latencies, throughput, and choose the right DB for your use case