How many ounces does it take to fill a 4 ton AC unit?

hard to say it depends on the unit if it is self contained like a package unit (one piece) at your house roughly figure about 2 pounds per ton if it is a split system (two pieces of equipment) just depends on how long the line set is and the seer rating of the equipment the larger the seer rating the more refrigerant the system will hold if it is a package unit should be a name plate the lists the amount or u can call a dealer with model number of the equipment and they can let you know