It varies from app to app and what the underlying hardware is. On "real" hardware, meaning not virtual CPUs and virtual threads, I've seen one Puma worker repla

It varies from app to app and what the underlying hardware is. On "real" hardware, meaning not virtual CPUs and virtual threads, I've seen one Puma worker replace 24 Unicorns. Most cloud (god I hate that word) providers will be giving you vCPUs, in those cases usually one Puma will replace 4-8 Unicorn workers. Your mileage may vary based on whether your app is more IO or CPU bound. Most Rails apps are incredibly IO bound, though.