Concrete Bag Calculator
Estimate bags of concrete needed for slabs, footings, post holes, and pads.
Estimate bags of concrete needed for slabs, footings, post holes, and pads.
Volume = length × width × (thickness ÷ 12). Divide by bag yield and round up. Always buy 5–10% extra for waste.
| Bag size | Approx yield |
|---|---|
| 80 lb | 0.60 cu ft |
| 60 lb | 0.45 cu ft |
| 50 lb | 0.375 cu ft |
About 45 bags of 80 lb concrete equal one cubic yard.
Yes — add 5–10% for waste, spills, and form irregularities.
80 lb bags are standard for slabs. 60 lb bags are easier to handle for one person.
Results are estimates for planning purposes. Verify with product labels and local requirements before purchasing materials.