How many bags of concrete will you need for 30 ft 30ft 3in thick?

Answer 1

10 80# bags will fill about 6 cubic feet, so 375 bags should fill 225 cubic feet (30 x 30 x 0.25).

ANS 2 -

At least in my area, it would be much cheaper ordering this to be delivered by a concrete truck.

An 80 lb. bag of concrete is 2/3 of a cubic ft. of concrete. 3 bags is 2 cu. ft. So for 225 cu.ft. youll need 338 bags of concrete.