Ok, please check my math. Something doesn't seem right.

mg/mg, hydro is 6 times as potent as codeine (phosphate). DHC is twice as potent as codeine. Therefore, hydro is 3 times as potent as DHC. If I am taking 40mg of hydro per day and want to change to DHC, I would have to take 120mg per day. I have the "continuous" 60mg DHC pills, so I would take 2 of these per day to get the same effect as 4 10mg hydros per day. Right?