minimum WD = ((powered strength+minimum damage of your weapon+minimum damage bonus from inventory items+attack damage bonus from inventory items)/100*(100+minimum damage bonus from inventory items %+attack damage bonus from inventory items %+WD skill bonus %)*classes WD)/2
maximum WD = ((powered strength+maximum damage of your weapon+maximum damage bonus from inventory items+attack damage bonus from inventory items)/100*(100+maximum damage bonus from inventory items %+attack damage bonus from inventory items %+WD skill bonus %)*classes WD)
minimum AR = ((powered dexterity+AR bonus from inventory items)/100*(100+AR bonus from inventory items %+AR skill bonus)*classes AR)/2
maximum AR = ((powered dexterity+AR bonus from inventory items)/100*(100+AR bonus from inventory items %+AR skill bonus)*classes AR)
minimum DF = ((powered strength+minimum defense of your inventory items+minimum damage from inventory items+attack damage from inventory items)/100*(100+minimum damage from inventory items %+attack damage from inventory items %+DF skill bonus %)*classes DF)/2
maximum DF = ((powered strength+maximum defense of your inventory items+maximum damage from inventory items+attack damage from inventory items)/100*(100+maximum damage from inventory items %+attack damage from inventory items %+DF skill bonus %)*classes DF)
minimum healing = (intelligence+strength+minimum of your healspell)/2
maximum healing = intelligence+strength+maximum of your healspell
For magic is same except the formula works with AS, HS, and mage stats. If you don't have inventory items min and max = 1.