Calculate how much concrete you need for your project. Choose your shape — slab, column, or footing — enter the dimensions, and get the volume in cubic yards plus the number of pre-mixed bags needed.
Volume Needed
1.23 yd³
33.3 cubic feet
80 lb Bags
56 bags
60 lb Bags
75 bags
40 lb Bags
112 bags
Add 10% extra to account for spillage and uneven surfaces.
Cubic Feet
Cubic Yards
Choose the bag size that works best for your project
112
bags needed
Yield: 0.30 cu ft/bag
~$392 est.
at $3.50/bag
75
bags needed
Yield: 0.45 cu ft/bag
~$338 est.
at $4.50/bag
56
bags needed
Yield: 0.60 cu ft/bag
~$308 est.
at $5.50/bag
A standard concrete truck holds about 10 cubic yards
12.3% of a truck
1.23 of 10 cu yd capacity
Small project -- mixing bags by hand may be more cost-effective than ordering a truck.
Standard concrete trucks deliver 10 cubic yards per load
Total Volume
1.23 yd³
Per Truck
10 yd³
Loads
1
Estimated costs for ready-mix concrete delivery
Best Case
$123
at $100/yd³
Average
$154
at $125/yd³
High End
$185
at $150/yd³
Cost Factors to Consider:
Timeline showing how concrete gains strength during the 28-day curing process
Day 1
16%
strength
Day 3
40%
strength
Day 7
70%
strength
Day 14
90%
strength
Day 28
100%
strength
Curing Best Practices:
Concrete is measured in cubic yards. To calculate the volume, the calculator multiplies length × width × depth for rectangular shapes, or uses π × r² × height for round columns. The result is converted from cubic inches to cubic feet, then to cubic yards (1 cubic yard = 27 cubic feet). Pre-mixed bag counts are based on standard yields: an 80 lb bag fills about 0.6 cubic feet, a 60 lb bag fills about 0.45 cubic feet, and a 40 lb bag fills about 0.3 cubic feet.
It depends on the volume of your project. An 80 lb bag of pre-mixed concrete yields about 0.6 cubic feet. For a 4-inch thick, 10×10 foot slab, you'd need about 56 bags of 80 lb concrete. This calculator does the math for you based on your exact dimensions.
Standard sidewalks and patios use 4 inches of concrete. Driveways should be at least 4-6 inches thick to support vehicle weight. Garage floors and areas with heavy loads should be 6 inches or more. Always check local building codes for requirements.
Yes, it's recommended to order 10% more than calculated to account for spillage, uneven ground, and forms that aren't perfectly level. Running short mid-pour can create weak cold joints in the finished slab.
Pre-mixed bags are cost-effective for small projects under 1 cubic yard (about 27 cubic feet). For larger projects, a ready-mix truck delivery is faster, cheaper per yard, and produces a more consistent result.
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