The number of 80 lb bags of concrete required for a slab depends on its size. Each 80-pound bag yields approximately 0.022 cubic yards of concrete. For a 4-inch thick, 100-square-foot slab, you'll need 56 bags. It's essential to calculate the volume based on your slab's dimensions. The weight of a cement bag can vary, depending on the type of cement being used and the size of the bag. Generally speaking, most cement bags will weigh between 40 and 50 pounds when they are full. This weight includes the material inside the bag and the bag itself. Enter the weight of a bag of cement available in your area to calculate the number of bags to fit the cement's calculated weight. If you want to estimate the material cost for the volume of mix you wish to make, you can also check it out in our calculator's Advanced mode . Formula for No. of bags of concrete do you need = total cubic yards ÷ bags yields in yards. To determine yields of premixed concrete bag (80lb, 90lb, 60lb, 50lb, and 40lb) in yards, divide the weight of one bag of concrete in pounds by 3600 (because one yard of concrete weighs about 3600 pounds). A 5-gallon bucket of cement will weigh in at 60lbs for the one bag of pre-mix plus the water's weight added to the mix. Typical concrete pre-mix will require about ½ gallon of water. That's about 4.17 pounds of water weight. Therefore a bucket of cement will weigh about 65 pounds. An 80-pound bag of concrete yields 0.60 cubic feet, or 0.0222 cubic yards, covering roughly 3.6 square feet up to a typical depth of 2 inches for excavation or backfills, and 1.66 bags of 80-pound concrete will yield 1 cubic foot of landfill. A bag of cement weighs 94 pounds. Concrete mix typically uses five bags of cement, or 470 pounds, per yard of concrete to be poured. Concrete mix includes rocks and sand along with cement. Cement is a masonry binding agent that hardens upon drying. How much does a bag of cement weigh? Q. How much does a bag of cement weigh? A. A bag or sack of cement is 94 lb (43 kg) in the United States; for other kinds of cement, a quantity is indicated on the bag. References: ACI 225R-19; ACI CT-23 Topics in Concrete: Cementitious Material A. A cubic yard of concrete's average weight is 4,050 lbs, or 150 lbs per cubic foot. Quikrete concrete bags come in 40lb, 50lb, 60lb, & 80 lb. Cement is a material used to make mortar and concrete and is usually sold in bags of various sizes. The most common bag size is 94 lbs (42.6 kg), but bags can range from as little as 40 lbs (18.14 kg) to as much as 94 lbs (42.6 kg). The weight of a bag of cement can also vary depending on the brand or type of cement. 2PmFYJ.