Concrete Volume & Bags
Slabs, footings, or sonotube piers — cubic yards and 60/80 lb bag counts.
Estimates only — verify with local code and the product label.
How this works
Concrete volume is just length × width × thickness, all converted to feet, giving cubic feet — divide by 27 to get the cubic yards a ready-mix truck would quote. This tool handles three common shapes: a slab (length, width, thickness), a continuous footing (total length, plus a width and depth usually given in inches), and a set of round sonotube piers (diameter, height, and count, using the circle-area formula π × radius²).
For small pours, bagged concrete is often more practical than a truck. Bag yield is a manufacturer-published number — a standard 60 lb bag yields about 0.45 cubic feet of mixed concrete, and an 80 lb bag about 0.6 cubic feet (Quikrete and Sakrete's own coverage charts both land here for their standard 6.0-6.5 bag mixes). Bag count is just your total cubic feet, with waste added, divided by that yield and rounded up.
A 10% waste allowance is the default here, which is standard for a hand-poured, smaller job — it covers spillage, slightly over-dug forms, and the reality that a truck or a stack of bags rarely divides evenly into exactly what a pour needs. Ready-mix companies commonly round order sizes up similarly.
This doesn't check rebar, wire mesh, vapor barrier, or whether your footing depth meets your local frost line requirement — those are still yours (or your contractor's) to confirm before the pour.
Frequently asked
60 lb or 80 lb bags — which should I buy?
80 lb bags cover more concrete per bag (fewer bags, same total weight to move), but each bag is heavier to lift. Small jobs where you're mixing by hand often go with 60 lb bags for that reason.
Does this account for frost depth on footings?
No — you tell it the footing depth. Minnesota's frost depth requirements vary by jurisdiction (commonly 42" or more); confirm the required depth with your local building department before you dig.
Questions about a project? Contact us.