Concrete Calculator
Figure the cubic yards of concrete for a slab, footing, round column or set of stairs, plus how many bags or truckloads it takes and what it costs.
- Before waste
- Cubic feet
- Cubic meters
- 80 lb bags
- 60 lb bags
- Weight
- Bags or truck?
- Cost
- Add a price to estimate
Pour List
Pours you add are saved in this browser.
| Pour | Size | Cubic Yards | 80 lb Bags | Cost | Remove |
|---|
How to Calculate Concrete
Concrete is ordered by the cubic yard. Work out the volume in cubic feet, divide by 27 to get cubic yards, and add a little extra for spillage, uneven ground and forms that bow out.
For stairs on the ground, each step is a solid block from the ground up: the first step is one rise tall, the second two rises tall, and so on, which is where steps × (steps + 1) ÷ 2 comes from. Convert inches to feet before multiplying.
Worked Example
Bag Yields
Bagged concrete mix yields about 0.0075 cubic feet per pound, per Quikrete's data sheet.
| Bag Size | Yield | Bags per Cubic Yard |
|---|
Slab Coverage
| Thickness | One Cubic Yard Covers | Cubic Yards per 100 Sq. Ft. |
|---|
Tips for Ordering Concrete
Order 5% to 10% extra; running short in the middle of a pour is far worse than having a little left over. Measure the forms, not the plans, since dug footings and uneven subgrade often hold more than you expect. Ready-mix plants often charge a short-load fee for small orders, and bags make more sense for jobs under about a cubic yard.
Common thicknesses are 4″ for patios and sidewalks and 5″ to 6″ for driveways that carry cars. Check local code and your plans for footings, reinforcement and anything structural.