How much capacity do you need?

Requests per second doesn’t size your backend — concurrency does. Enter your peak traffic and response time and get the concurrency required (Little’s Law), the workers and instances to provision, and the headroom to survive a burst.

The number that actually sizes your backend

Teams provision by requests per second and then get surprised when a perfectly adequate-looking server falls over — because the thing that exhausts a server is not the request rate, it’s how many requests are in flight at once, which is the rate multiplied by how long each one takes. A slow endpoint at modest traffic can need far more capacity than a fast one at high traffic. Little’s Law makes that concrete, and headroom turns a fragile fully-loaded estimate into one that survives a Monday-morning spike.

Sizing is the easy, static part. Knowing your real concurrency and latency as they shift, and adding or shedding capacity before users feel it, is the ongoing version — the kind of live capacity awareness a control plane gives you over the infrastructure you own.