Guessing Server Capacity Is a Costly Mistake
When launching a new service or handling rising traffic, sizing servers "just to be safe" either wastes budget on idle capacity or, worse, leaves you crashing under a sudden traffic spike. Capacity planning can start with just two numbers: expected requests and response size.
This calculator converts your daily requests into average requests per second (RPS), then assumes real traffic spikes to about 3x that average during peak hours. From that peak RPS, it estimates the bandwidth you need and a rough server tier — small, medium, large, or multi-server.
These numbers are a starting estimate, so always validate with real load testing before you deploy. If your traffic includes a lot of images or static files, adding a CDN can dramatically reduce the load on your origin server too.
Frequently Asked Questions
Real traffic is never evenly spread across the day and tends to spike during certain hours, so a 2-3x peak multiplier over the average is a common industry rule of thumb for safe capacity planning.
It is simplified into small (1-2 vCPU), medium (4 vCPU), large (8-16 vCPU), and multi-server tiers based on the peak requests per second. Always validate with real load testing before deployment.
Yes. When a CDN handles static content, the requests and bandwidth your origin server must absorb drop significantly, often allowing a smaller server tier.