After you build your first bow you can use this to hit your target # on the next one.
My numbers are for a recurve.
My stack was .257 made a 45# bow, enter the pound bow you want 38# Boom .243 stack
Now I have 2 stack numbers -----Keep a log book .257=45#---.243=38# and so on
If you can show us what kind (picture) of a bow/form we may get you close on the first one.