I ended up having it easier than @neonthewrite in my calculations, which is good since at first I just went “Four inches sounds perfect!”
Sam is 6′4″ tall, making him 76 inches tall. 76/4=19.
So our scale is 1:19.
Dean is 6′1″ tall, so taking his 73 inches into account and dividing by 19 makes him only 3.84 inches tall, and our shortest character in the BL crew to his chagrin.
In the opposite direction, Jacob is 6′5″ tall, so 77 inches multiplied 19 times over makes him 1463 inches tall as a giant, or about 122 feet tall! It’ll take a lot of food to keep him fed!
I went to school for physics and sometimes that bachelor degree in science comes in useful. Not as often as I’d like, but I do enjoy a little math fun from time to time.
For @neonthewrite, her Bowman stands 6′2″ tall if he was human-sized, which gives her an awkward scale of 1:18.5, so the numbers aren’t as pretty to work with but you can still figure it out. Sam might look the same height as Bowman while they’re standing together, but he’s technically taller.