Insulating? how do we figure out how lots bags of blown insulation we...

how do we figure out how lots bags of blown insulation we are going to call for?
Hole surrounded by the wall contained by a...
Answers:    It is recamended @ least 17" within an atic, do your math ??SQ.ft ??
6 cubic foot of concrete; deliver or purchase...
you will need the square foodage of your attic after decide what r expediency you want , the higher the r meaning the better. the bag will register the the square footage it will cover at that r value, later purchase the number of bags to cover your square footage.