The amount of Bandwidth offered by Bluehost depends on the type of hosting plan one purchases. The lowest bandwidth is not set but it’s regulated while the maximum bandwidth depends on the type of a server a website is allocated. The starter plan which is the cheapest plan in Bluehost has unmetered bandwidth, meaning that if your site a uses more than a certain amount of bandwidth, you will get a message from the Bluehost to upgrade your plan. One consequence of exceeding the bandwidth limit is that your site will either be slow or go offline as it affects other sites within the server.
Bluehost says that 99.95% of their customers do not exceed the bandwidth set for each customers, which is why they haven’t set a limit. However, when one is on shared hosting plan, the company has to monitor resource usage for each blog. If they realize that one of the sites in a particular server is using more resources than others, Bluehost sends an email advising the owner to upgrade to a dedicated or VPS server which don’t have as many sites as those in Shared Hosting plan. Dedicated server is the most recommended plan because each site hosted under this plan does not share resources with other sites, but it’s more expensive than shared or VPS plans.
When you compare VPS, Dedicated Server and Shared hosting, it’s only Dedicated Server Hosting that will provide 100% bandwidth, PS provides up to 50% while Shared hosting provides up to 10%. In Shared Hosting if a site uses more than 50% of the bandwidth, Bluehost will have to notify the owner to upgrade to VPS or Dedicated Server.
In case you receive an email from Bluehost to reduce bandwidth usage, the best thing to do is to ensure the images you use are light. You can use Smush Pro plugin to reduce the size of all images on your site. You should also ensure that you change the template you use. Light WordPress Themes translate to low bandwidth usage and vice versa. In addition, ensure that you reduce the number of plugins on your site.
One thing you should know is that no matter what you do at your site, if the traffic continues growing, the bandwidth usage must also increase. It will reach a point where you have to upgrade from shared hosting to dedicated server especially if the number of visitors to your site increase to more than 30,000 per day.