Check out this article from the Forbes website to learn more about EFCs: https://www.forbes.com/sites/troyonink/2017/01/08/2017-guide-to-college-financial-aid-the-fafsa-and-css-profile/#321a4c554cd4
The tables in the article are from 2017-2018, but should give you a basic understanding of how EFCs are calculated.