Approaching to the unmanaged world is not always easy, and it's definitely hard, for a newbie, realize how many resources he will need for his setup. We have lot of variables but I'm pretty confident that, after reading this, you will have a better idea of your needs. Exactly like a normal PC a VPS has some RAM, bandwidth, CPUs and so on. But how much of them do I need? Those are the sizes offered by the company, starting from €1: arubacloud.com Let's start from the classical use: the web server. I actually like more nginx than apache, because it uses much less resources, and soon you'll see why. A web server, usually has three components: an HTTP server (nginx in our case) a dynamic pages engine (PHP) the database server (MySQL) You can live without the last two if, obviously, you intend to only serve static pages. Yes, that means no wordpress! In this case, the size S will be more than enough because nginx, with those resources, can easily serve hundreds of people simultaneously. If you want or need php and sql, then it will be a pretty different story. You will need to choose your size on how much traffic you expect to have. You will need 200MB of RAM for MySQL, another hundred for nginx, and half hundred for each PHP process. For a website with a few thousands requests per day, the S will still be enough. From this point on, however, you should monitor your average CPU usage; if this is approaching or already is 100%, you will need to choose an L to get another core, otherwise an M will do the trick. Let's now talk about mail servers. A mail server usually haves: an SMTP server (postfix) an IMAP server (POP3? nah...) a daemon scanning for spam and viruses eventually, a MySQL database storing users and other data I can already say you will need lots of RAM for this. My tests revealed that a VPS with postfix, dovecot and amavis, has more or less an hundred MB of free RAM from a total of 1024. The virus scanner uses lots of ram and, avoiding it, you can save a lot. Optimizing your setup you could be able to also fit MySQL on an S, but I discourage doing so. If you need a webserver and a mailserver, my advice is to get two Ss, so you can split the load between the two, and keep MySQL with the webserver, which is obviously a more efficient setup. This kind of setup can tolerate 25-50 users simultaneusly. For both use-cases, however, the XL is a nice choice if you have a business to build up on webservices like small hosting or mail hosting or you think you will have lots of active users. It's very hard to spend all the resources this size offers, especially if your setup is correctly done.