Concrete Bag Calculator (40 lb, 60 lb, and 80 lb Yields)
Calculate the exact number of 80 lb, 60 lb, or 40 lb pre-mixed concrete bags required for slabs, shed pads, and walkways—plus compare bagged vs. ready-mix truck delivery.
Interactive Material & Cost Estimator
HomeYardMath.com — Hardware Store Shopping List
Quick Reference Coverage Chart (Concrete & Masonry)
Instant pre-calculated material estimates for common US residential project sizes before compaction buffer:
| Typical US Project | Area | Depth | Volume | Weight | Store Bags |
|---|---|---|---|---|---|
| Trash Can / AC Condenser Pad (4 ft × 4 ft × 4") | 16 sq ft | 4 inches | 0.20 cu yd (5.3 cu ft) | 790 lbs | 9 bags (80 lb) or 12 bags (60 lb) |
| Hot Tub Pad (8 ft × 8 ft × 4") | 64 sq ft | 4 inches | 0.79 cu yd (21.3 cu ft) | 3,160 lbs | 36 bags (80 lb) or 48 bags (60 lb) |
| Small Shed Slab (10 ft × 10 ft × 4") | 100 sq ft | 4 inches | 1.23 cu yd (33.3 cu ft) | 4,940 lbs | 56 bags (80 lb) or 75 bags (60 lb) |
| Backyard Patio Slab (12 ft × 16 ft × 4") | 192 sq ft | 4 inches | 2.37 cu yd (64.0 cu ft) | 9,480 lbs | 107 bags (Order Ready-Mix Truck!) |
| RV / Heavy Driveway Apron (12 ft × 20 ft × 6") | 240 sq ft | 6 inches | 4.44 cu yd (120.0 cu ft) | 17,780 lbs | 200 bags (Ready-Mix Required) |
Engineering Formula & Material Density Constant
Standard cured Portland cement concrete weighs approximately 148 to 150 lbs per cubic foot (4,000 lbs or 2.0 US tons per cubic yard). One 80 lb bag yields 0.60 cu ft (45 bags per cubic yard); one 60 lb bag yields 0.45 cu ft (60 bags per cubic yard); one 40 lb bag yields 0.30 cu ft (90 bags per cubic yard).
How Many Bags of Concrete Make a Cubic Yard? (40 lb, 60 lb, 80 lb)
Every pre-mixed concrete bag at Home Depot, Lowe's, or Menards yields a fixed wet volume once mixed with water:
- 80 lb Bag (0.60 cu ft yield): Takes exactly 45 bags to make 1 cubic yard (27 cu ft). At 4 inches thick, one 80 lb bag covers 1.8 square feet.
- 60 lb Bag (0.45 cu ft yield): Takes exactly 60 bags to make 1 cubic yard. At 4 inches thick, one 60 lb bag covers 1.35 square feet.
- 40 lb Bag (0.30 cu ft yield): Takes 90 bags to make 1 cubic yard. At 4 inches thick, one 40 lb bag covers 0.90 square feet.
For cylindrical deck piers, use our dedicated Sonotube Footing Calculator, or for wood fences check our Fence Post Hole Concrete Calculator.
Bagged Concrete vs. Ready-Mix Truck: The 1.5 Cubic Yard Cutoff Rule
One pallet of 80 lb concrete holds 42 bags (3,360 lbs) and yields 0.93 cubic yards. While 45 bags of 80 lb concrete cost roughly $290—which looks cheaper on paper than ordering a single cubic yard from a ready-mix truck ($165/yd³ + $175 "short-load fee")—mixing 50+ bags by hand in a wheelbarrow or 3.5 cu ft drum mixer takes hours. If the first corner of your slab begins setting before you pour the last bag, you will get weak cold joints. Any flatwork slab larger than 1.5 cubic yards (68 bags / ~120 sq ft at 4" thick) should be poured via ready-mix truck or volumetric mobile mixer.
Frequently Asked Questions
How many 80 lb bags of concrete do I need for a 10x10 slab?
A 10 ft × 10 ft slab poured 4 inches thick requires 33.33 net cubic feet (1.23 cubic yards) of concrete. That equals 56 bags of 80 lb concrete before waste, or 62 bags of 80 lb concrete with a 10% sub-grade waste buffer.
How many 60 lb bags of concrete are on a pallet?
A standard big-box store pallet holds 56 bags of 60 lb concrete (weighing 3,360 lbs total and yielding 25.2 cubic feet, or 0.93 cubic yards).
Should I pour a 4-inch or 6-inch concrete slab?
Use a 4-inch thickness (with 6x6 wire mesh or #3 rebar) for pedestrian sidewalks, patios, and garden sheds. Upgrade to 5 or 6 inches with #4 rebar on 18-inch centers for garages, carports, RV pads, and heavy vehicle driveways.
How much water do you mix per 80 lb bag of Quikrete?
Approximately 3 quarts (6 pints / 0.75 gallons) of clean water per 80 lb bag, up to a maximum of 4.5 pints for a 60 lb bag.