Concrete Bag Calculator
Calculates premixed bag requirements across all commercial bag sizes (40 lb, 50 lb, 60 lb, 80 lb, and 50 lb Fast-Setting Quikrete) with water mixing volumes and pallet counts.
Formula
Volume (cu ft) = L × W × (D ÷ 12); Bags = Ceil(Volume × (1 + Waste %) ÷ Bag Cu Ft Yield)
1. Net Volume = Length ft × Width ft × (Depth in ÷ 12) 2. Volume with Waste = Net Volume × (1 + Waste %) 3. Yield per Bag: 80 lb = 0.60 cu ft; 60 lb = 0.45 cu ft; 50 lb = 0.375 cu ft; 40 lb = 0.30 cu ft 4. Bags to Order = Ceil(Volume with Waste ÷ Bag Yield)
Inputs
- Length
- Width
- Thickness / Depth (Inches)
- Concrete Bag Size
Worked example
Pouring an 8 cu ft equipment pad using 80 lb bags of high-strength concrete mix.
Outcome: Net volume is 8.0 cu ft. With 10% waste (8.8 cu ft total), dividing by 0.60 cu ft per 80 lb bag gives 14.67 bags, rounding up to 15 full 80-lb bags. Total water: ~9 gallons.
How much water does an 80-lb bag of concrete take?
An 80-lb bag of concrete mix typically requires 2.5 to 3.0 quarts (about 0.75 gallons) of clean water. Adding too much water makes the concrete easier to work with but drastically reduces its PSI rating and increases cracking.