It will all depend on if you have a different cooler and what not. IIrc it will hold approximately 12 quarts. Just keeping adding and checking until you have it full. Check in your Haynes or Chilton manual, it will tell you total capacity in stock trim.
That AINT 12 qts in the pan, it is 12 qts TOTAL. About half of that amount stays in the converter.
In other words.....if all you did was drain the pan, don't dump 6 more quarts in there. About one more aught to do it.
Like the man said, put in another and recheck.