How much paint to buy?

All right, guys, it is almost time to paint the sol. I have my color picked out and where to get it. Now all I need to know is how much to buy? I want to do about three coats of basecoat and about four coats of clear. How much paint should I get? I also want to paint my door jambs and the engine bay, too. Or at least I want to have enough paint to have that option. So anyone out there who has painted there sol, how much will I need?