Every capacity conversation starts the same way: someone quotes a number from a blog post written for a workload nothing like theirs.
Instead, measure three things before you buy — sustained CPU during your busiest hour, working-set size rather than total data size, and the read/write mix hitting your disk. We walk through pulling each of these off an existing server with tools already installed.
The rule of thumb we keep coming back to: size for the 95th percentile, not the peak, and leave the peak to autoscaling.
