Although it is JavaScript based, Google Charts has a couple of options to make your charts entirely in PHP. You can either use server-side code (in our case PHP) to get the data, or get one of the open-source wrappers to do it for you.
Source: 4 Best Chart Generation Options with PHP Components – SitePoint
Need to generate charts for the baseball-handbook.com website and looking into php options. Google seems like the simplest solution right now. The above site breaks down each option nicely.
Here’s more info about Google Charts.