Really it depends on what type (AG or Extract) and size boil if extract. I would sugest punching the numbers it to one of the homebrew programs out there and then locking the ingredients to the batch size and then double the batch size, with promash, every time that i have done that it just doubles everything. but you can also adust by a gallon or two if you need to add a little bit of volume for losses.
"Yes, I am a pirate two hundred years too late. The cannons don't thunder there's nothin' to plunder,
I'm an [under] forty victim of fate, Arriving too late, arriving too late."