Concrete slab calculator
Get concrete volume, bag counts, and material cost from your dimensions and your own local supplier price.
Concrete slab calculator
Enter finished slab dimensions. Waste is added after the geometric volume is calculated.
Concrete material cost
Enter the price per cubic yard from your local supplier quote. The calculator does not assume a national price.
Formula: length × width × thickness, converted to cubic yards, plus waste. Cost outputs use only the prices you enter; taxes, permits, and contractor markup are not assumed.
Concrete slab cost calculator
The material-cost result is your calculated concrete volume multiplied by the price per cubic yard you enter. It does not invent a national average or silently add labor, delivery, tax, reinforcement, demolition, or permits.
How the volume calculation works
We multiply length by width by thickness, convert inches to feet, then add your waste allowance. There are 27 cubic feet in one cubic yard. An 80 lb bag is modeled at 0.6 cubic feet and a 60 lb bag at 0.45 cubic feet.
Two check examples
| Slab | Waste | Result |
|---|---|---|
| 20 × 20 × 4 in | 10% | 5.43 cu yd / 245 80 lb bags |
| 12 × 12 × 4 in | 10% | 1.96 cu yd / 88 80 lb bags |