Capacity Planning

Estimating and preparing the resources a system needs to handle expected and peak load safely.

Capacity Planning diagram

Where it fits

Capacity planning connects system design, traffic forecasts, infrastructure cost, and reliability. It asks whether the system has enough compute, storage, network, queue, and database capacity for normal and peak demand.

Mental model

Capacity is a budget. Every request spends some CPU, memory, I/O, network, database, and human operational attention. Capacity planning estimates those budgets before users discover the limits for you.

Example

Before a launch, a team estimates peak requests per second, database write volume, cache hit rate, queue backlog tolerance, and rollback capacity. That planning determines whether to scale horizontally, increase limits, add caching, or simplify the launch.

Common mistakes

Planning only for average load instead of peak load.
Forgetting downstream dependencies and quotas.
Treating autoscaling as a substitute for understanding bottlenecks.

Scalability, bottleneck, autoscaling, latency, observability, and load testing.