There's no real way to calculate what the perfect bioload is. A snowflake eel can get up to 3 to 3 1/2 feet! Tangs poop a lot!!!
If I didn't know how much to put in a tank before reaching it's limit, I would have a very light bioload. You should only add one fish at a time until you "feel" that your tank has reached it's limit.
Don't know exactly how to describe it because the rule of 1" of fish per 10g no longer exists... (because of the breakthroughs of filtration)