[nytrainer]

Most higher quality base coat are a 1:1 mix with reducer so 1 qallon base gives you 2 gallon (8 qts) sprayable but “cheaper” base coat mix 2:1 so 1 gallon base is only 6 qts sprayable.
A sprayout card will let you know how many coats for full coverage. Certain colors can mean more or less coats. Also if I buy more than a gallon I mix them together in a 3.5 gallon metal pail to make sure they are one color (I’ve seen slight color variations when buying 1 gallon and extra qt or 2 from same jobber).
Adding jambs, door frames, underneath deck lid, roof, etc need to be considered.
I always like to have a couple pints of base left over for future.