How much paint do I need to buy?

[Dusty_case]

Hello I am looking to find out roughly how much paint I will need to buy. I am thinks of a metallic blue but it is $$$ so if I had an idea of how much paint, clear coat, and hardener if needed to buy I can make budget. Will I need hardener or is there a easier way to find out? I suck at math I tryed doing a formula on a web sit I just didn't have to much luck with it.


P.s. It is a 68 c10 long box pickup and I am painting it 2 tone white on top and blue on bottom