The Concrete Bags Calculator tells you exactly how many bags of pre-mixed concrete to buy for any project — whether you know your slab dimensions, tube footing size, or just want to enter a volume directly. Choose from 40 lb, 60 lb, 80 lb, and 90 lb bag sizes (results for all four sizes shown simultaneously), toggle th..
Yields: 40lb=0.30 CF · 60lb=0.45 CF · 80lb=0.60 CF · 90lb=0.675 CF
US avg: 80lb bag ~$6–$9 at home improvement stores (2025)
RESULTS — 80lb BAGS (+10% WASTE)
BAGS NEEDED (80lb)
62
bags
40 LB BAGS
123
60 LB BAGS
82
80 LB BAGS
62
90 LB BAGS
55
EST. MATERIAL COST (80lb)
$432.76
at $6.98/bag x 62 bags
BAG VISUALISER (showing 20 of 62 bags)
VOLUME SUMMARY
BAG YIELD REFERENCE
0.30 cu ft
Quikrete 40lb
0.45 cu ft
Quikrete 60lb
0.60 cu ft
Most common
0.675 cu ft
Fast-setting
KEY FACTS
1 CY = 27 cubic feet
1 CY = 45 x 80lb bags
1 m³ = 35.3 cubic feet
80lb bag ~$6–$9 at Home Depot / Lowes
Always order 10% extra
Bags best for pours under 1 CY
Order ready-mix for 1 CY or more
Choose your calculation mode. 'From Dimensions' lets you enter your project measurements directly — pick Slab, Tube/Column, or Footing. 'Enter Volume' is for when you already know your volume in cubic yards, cubic feet, or cubic metres. 'Bags to Volume' works in reverse: enter how many bags you have and find out how much concrete they will make.
Select your bag size — 40 lb (0.30 cu ft), 60 lb (0.45 cu ft), 80 lb (0.60 cu ft), or 90 lb (0.675 cu ft). The 80 lb bag is the most common for DIY work. If you are mixing by hand, the 60 lb bag is easier to manage. Results for all four bag sizes are shown simultaneously so you can compare.
Toggle 'Add 10% waste allowance' on (recommended). Concrete waste happens due to uneven sub-base, spillage, and rounding — running short mid-pour creates a structurally weak cold joint. Always buy 10% more than the calculated amount.
Optionally enter the price per bag to get a material cost estimate. US average for an 80 lb bag of Quikrete or Sakrete is $6–$9 at Home Depot or Lowes in 2025. Prices vary by region and store.
Read your results. The large green number shows bags needed for your selected bag size. The grid below shows all four bag sizes at once. The 'Key Facts' panel on the right confirms that 1 cubic yard needs 45 x 80 lb bags — useful for cross-checking your result.
How many 80 lb bags for a 12 ft × 16 ft patio, 4 inches thick? Step 1: Calculate volume in cubic feet 12 ft × 16 ft × (4 ÷ 12) ft = 12 × 16 × 0.333 = 64 cubic feet Step 2: Convert to cubic yards (optional check) 64 ÷ 27 = 2.37 cubic yards Step 3: Add 10% waste 64 × 1.10 = 70.4 cubic feet Step 4: Divide by bag yield (80 lb = 0.60 CF per bag) 70.4 ÷ 0.60 = 117.3 → order 118 bags Step 5: Cost estimate at $7.50/bag 118 × $7.50 = $885 in bags NOTE: At 2.37 cubic yards, this project is above the 1 CY threshold where ready-mix becomes cheaper. Ready-mix at $140/CY × 2.37 CY × 1.10 waste = $365 delivered — less than half the bag cost. Use this calculator to decide whether bags or ready-mix makes more sense for your project.
Last updated: April 29, 2026 · Formula verified by EagleCalculator team · Eagle-eyed accuracy for every calculation.