Lactose is 100% unfermentable, and has a PPG of about 36. That means a pound in 5 gallons will raise your OG and FG by about 7 points. I would imagine that Beertools is using it to calculate the OG, but then just calculates the FG as a percentage of the OG based on the yeast you choose (% Apparent attenuation), without taking the ingredients into account.
Holy cow- you guys did it. The Kickstarter was successfully funded! Now the real work
Monticello Barleywine, Red Nosed Tripel
Cali Common, Imperial Common, Sunshine Belgian Rye, Sticke Note Alt
Cherry Blackberry melomel
Belma Pale Ale, Cluster Fug IIPA, American IIPA v1.0, rauchbier, roggenbier