Concrete planning

Estimate concrete for a rectangular slab.

Enter slab length, width and thickness to see base volume, an explicit waste allowance and an approximate 80 lb bag count.

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Planning results

Base volume
1.48 yd³
Order volume
1.63 yd³
Estimated bags
74
Estimated material cost
—
Volume = length × width × depth

Bag count uses an approximate yield of 0.60 ft³ per 80 lb bag.

From slab dimensions to an order quantity

Convert thickness into the same linear unit as length and width, then multiply all three dimensions. The calculator shows base volume before multiplying by the waste factor.

Example: A 12 ft × 10 ft slab at 4 in thick is about 1.48 yd³ before waste and 1.63 yd³ with a 10% allowance.

Important limitation

Bag yield is an approximation based on 0.60 cubic feet per 80 lb bag. Product yield, slab geometry, site conditions and supplier minimums vary; confirm before ordering.

Reference: QUIKRETE Concrete Mix product data.

Last reviewed 8 September 2026.

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