That depends. For a small website with low traffic, 2GB of RAM is likely enough to get you started. But if you have a massive site with over a million pageviews per month, you’ll need anywhere between 8GB and 16GB of RAM, possibly more. And with this volume of traffic, CPU power and caching technology are just as important as RAM. The best way to decide is to monitor your current CPU and RAM usage, and make an educated guess based on your expected growth. It doesn’t have to be a perfect decision. Most VPS providers let you scale up or down almost instantly, so you can always add or remove RAM as necessary.