When purchasing a server or a hosting plan, you’re usually offered bandwidth choices: 20GB a month, 100GB, whatever it may be. But how much do you need, exactly?

It’s always better to have a larger allowance than you need, because when you run over, one of two things will happen: you will be charged (usually for each GB that you go over), or your service will be suspended. Neither of them are viable options for most people.

One question to ask your host is how bandwidth is charged. Are you charged for incoming and outgoing traffic, or just outgoing? This will be a key element in your decision-making process. For many sites, as little as 20GB will do, but for the more popular sites, more bandwidth will be needed. Most dedicated hosting plans offer 1000-1500 GB of monthly bandwidth, and this is usually good enough for most hosts. If you run a site that eats up more bandwidth than this, you likely will need to consider other options, such as load balancing.

One good idea is to start off with an amount you estimate will be appropriate for your site, say 40 GB. Then, monitor your bandwidth. If it looks as if you’ll go over before your month is over, arrange with your host to add more bandwidth. Soon, you’ll have an idea of how much bandwidth your server consumes on average. Then, add another 10GB to be safe, and you’ll have a pretty good idea of what’s good for you. So, if your server typically eats up 15-20 GB a month, go for 25GB or 30GB. That way, if you experience a sudden spike, or temporary increase in popularity, you won’t be as likely to be hit with hefty overage charges.