Home & Construction · Material volume
Calculate concrete volume for slabs, footings, walls, columns, post holes, and known-volume jobs. See cubic yards, metric volume, approximate bag counts, and an optional extra allowance.
Enter a pour type and dimensions to calculate concrete.
| Bag size | Reference yield | Bags needed |
|---|---|---|
| 40 lb | 0.30 ft³ | — |
| 50 lb | 0.375 ft³ | — |
| 60 lb | 0.45 ft³ | — |
| 80 lb | 0.60 ft³ | — |
| Custom yield | Entered above | — |
Reference yields follow QUIKRETE Concrete Mix Product 1101 published approximate yields. Products vary; verify the yield on the bag or manufacturer data before ordering.
It turns the dimensions you enter into net concrete volume, then keeps that measured volume separate from the optional extra allowance. Results include cubic yards, cubic feet, cubic meters, liters, and approximate bag counts.
Slabs, footings, walls, and rectangular columns use length × width × height/depth/thickness. Round columns and post holes use π × radius² × height or depth. Repeated identical pours multiply that volume by Quantity.
One cubic yard equals 27 cubic feet. Ready-mix concrete is commonly discussed in cubic yards in the U.S.; this app converts your geometry but does not model supplier minimums, truck capacity, pricing, or delivery rules.
Net volume is the geometry you entered. Concrete to order adds the allowance you choose. The default 10% is editable and is not a universal construction rule; uneven forms, excavation, spillage, and measurement uncertainty can change actual usage.
A 10 ft × 10 ft slab at 4 in thick is 33.33 ft³, or about 1.23 yd³ net. With a 10% allowance, the modeled order volume is about 1.36 yd³. At the 0.60 ft³ reference yield, that is 62 × 80 lb bags.
This is a geometry/material estimate. It does not tell you what slab or footing size is structurally required, verify code compliance, design a concrete mix, estimate rebar or cost, or determine delivery quantities. Verify final dimensions, product yield, and ordering requirements with the appropriate supplier or qualified professional.
Calculate the shape's volume in consistent units, convert cubic feet to cubic yards by dividing by 27, then apply only the extra allowance you actually want to include.
At the 0.60 ft³ reference yield used here, 27 ft³ ÷ 0.60 ft³ per bag = 45 bags. Actual products can differ, so check the bag label.
Order volume adds your chosen allowance to the measured geometric volume. Set the allowance to 0% when you do not want an overage in the estimate.
Yes. Enter a custom yield in ft³ per bag or liters per bag; the custom bag count is rounded up.
No. It calculates material volume only and does not perform structural or code design.
