I have a 2010 F150, it has 4 built in cargo hooks in the truck bed. How can I find out the capacity of those hooks?

 

If it is original equipment, maybe a Ford dealership might be able to provide a reliable answer.
If it is "add on" , a lot will depend on the size of the fasteners, the size of the hooks, and could be painful , where they were made.

 

Assuming you are talking about the plastic hooks that have lock in, I have not seen any capability specs for them, personally I would not use them for more then say 200 lb using all four, I would not use them for a motorcycle or a quad.
It may say in your owners manual but I do not know since all vehicles do not come with them.