System Design Calculator

System Design Calculator helps engineers make fast back-of-the-envelope estimates for architecture planning and interviews. Use focused calculators for common system design questions: - Users and traffic: convert daily active users into average and peak QPS. - Storage: estimate retention, replication, and index overhead. - Bandwidth: calculate ingress, egress, and monthly transfer. - Throughput and concurrency: apply Little's Law to request load. - Cache sizing: estimate hot working sets for Redis or Memcached. - RAM per server: size memory for sessions and connection state. - Media streaming: estimate bandwidth and storage for audio and video services. - AI inference: estimate GPU memory and throughput requirements. - WebSocket and real-time systems: estimate fan-out, connection memory, and server count. The app supports shorthand numeric input such as 10k, 1.5m, and 2B, includes compact and full-size layouts, and keeps calculations local on your Mac.