I put together a practical breakdown of how many users a small 1 vCPU + 2 GB RAM server can realistically handle. The answer isn’t simply “X users” because it depends heavily on the workload, application stack, caching, database usage, concurrent requests, and whether you’re serving static or dynamic content. For anyone running small self-hosted services or websites on inexpensive VPS instances, this may be useful
Just for comparison, my VPS server has ~20 active email boxes (postfix,dovecot,spamassassin,clamav), a few small-ish active wordpress sites (apahce,php-fpm,mariadb), radicale and some other smaller services running with 2 cores and 4GB RAM and it’s mostly just fine. Occasionally, specially during heavier updates on wordpress-sites, memory tends to get pretty full, but it’s still just fine. Tweaking memory cache for php (or running something else than php) would increase performance by a lot, but even without optimization the 5€/month VPS is quite capable to keep your internet presence around and on your own hands.