Slabs, driveways, patios, and footings
Concrete Cubic Yard Calculator
Calculate concrete volume, weight, 60 lb bags, 80 lb bags, cost, and a 10 percent overage recommendation.
Calculate Concrete
How to Calculate Cubic Yards of Concrete
- Measure the slab or footing length in feet.
- Measure width in feet and thickness in inches.
- Convert thickness to feet, multiply all three dimensions, then divide by 27.
Common Concrete Project Reference Table
| Project | Size | Cubic yards |
|---|---|---|
| Slab | 10x10 at 4 in | 1.23 |
| Driveway | 10x20 at 4 in | 2.47 |
| Patio | 10x10 at 4 in | 1.23 |
| Garage floor | 20x20 at 4 in | 4.94 |
| Sidewalk | 12x12 at 4 in | 1.78 |
Concrete Bag Calculator Table
| Bag size | Bags per cubic yard | Best for |
|---|---|---|
| 60 lb | 45 | Small pads and repairs |
| 80 lb | 34 | Small slabs and posts |
For full slabs, compare bag cost and labor against ready mix delivery. Bagged concrete is convenient, but mixing dozens of bags is slow.
Worked Example: Standard Driveway
A 10 ft by 20 ft driveway at 4 inches thick uses 10 x 20 x 0.333 / 27 = 2.47 cubic yards. With 10 percent overage, order about 2.72 cubic yards before applying supplier minimums.
FAQ
Multiply slab length by width by thickness in feet, then divide by 27. Use the 4 inch, 6 inch, and 8 inch buttons for common slab depths.
A cubic yard takes about 34 bags of 80 lb concrete mix. Always round up because partial bags are not practical.
A cubic yard takes about 45 bags of 60 lb concrete mix. For larger work, ready mix delivery is usually easier.
Many patios, sidewalks, and light slabs are 4 inches thick. Driveways and heavier slabs often use 5 to 6 inches or more.
Concrete weighs about 4,050 lbs per cubic yard. That is about 2.03 tons per cubic yard.
Yes, 10 percent extra is a practical starting point. Extra concrete covers uneven subgrade, waste, and small measurement errors.
Many ready mix trucks carry around 8 to 10 cubic yards. Minimum order and short load fees vary by supplier.
Yes, enter footing length, width, and depth. For multiple footings, calculate each shape and add the totals.
It is slightly more than 1 cubic yard. A 10x10 slab at 4 inches needs about 1.23 cubic yards before overage.
No. The calculator estimates concrete volume, weight, bags, and cost only. Confirm structural details with your contractor or engineer.