Free concrete calculator · No signup
Get cubic yards, cubic feet, and pre-mix bag counts for slabs, footings, walls, and round columns — with a waste factor built in.
Estimates only. Confirm with your ready-mix supplier; bag yields vary by mix.
Concrete is ordered by the cubic yard. To find your volume, multiply length × width × thickness (all in feet) to get cubic feet, then divide by 27 to get cubic yards. For a slab or footing, keep length and width in feet and enter thickness in inches — the calculator converts it. For a round column, it uses π × radius² × height.
Always add a waste factor. Subgrade is never perfectly level, forms bulge, and some concrete is lost to spillage and the chute. 5–10% is typical; this tool defaults to 10%. Under-ordering means a cold joint or a second short-load fee, so it's cheaper to round up.
Bagged vs ready-mix: bag counts are shown for small jobs, but past about half a yard, ready-mix delivery is faster and cheaper. Field PM tracks the quantities you actually place on the daily report so your productivity by cost code reflects real yields, not estimates.
There are 27 cubic feet in one cubic yard. To convert, divide total cubic feet by 27. This calculator does it for you and also reports cubic feet for reference.
An 80 lb bag of pre-mix yields about 0.60 cubic feet, so a cubic yard (27 cu ft) takes roughly 45 bags. A 60 lb bag yields ~0.45 cu ft (~60 bags/yd) and a 40 lb bag ~0.30 cu ft (~90 bags/yd). Bags are only practical for small pours — order ready-mix above roughly half a yard.
Most contractors add 5–10% for spillage, uneven subgrade, and over-excavation. This calculator defaults to 10%. For rough or hand-dug footings, consider 15%.
Bagged concrete makes sense for very small jobs — a few footings, a small pad. Once you're past about half a cubic yard, ready-mix delivery is cheaper and faster. Most ready-mix suppliers have a minimum load and short-load fee, so check before ordering.
Field PM builds the math into the platform — job costing, billing, and forecasting from real field data. 14-day free trial, no credit card.
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