Why add a waste factor?

Concrete is never placed in a perfectly controlled environment. Some spills during placement, over-excavation at edges, and irregular sub-base mean you typically need 5-10% more material than the theoretical volume.

How many bags per cubic yard?

One cubic yard of concrete requires approximately 45 bags of 80 lb mix, 60 bags of 60 lb, or 90 bags of 40 lb. Pre-mixed bags are convenient for small projects under 1 cubic yard.

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Concrete Calculator

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Wastage %

Mix Ratio C:S:A

Length (ft)

Width (ft)

Depth (in)

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Calculate concrete for slabs, columns, round slabs, footings, and walls. Results in cubic yards, cubic meters, and bag counts (40/60/80 lb). Adjustable waste factor. Material breakdown.

How to Use

1Select the shape: Slab, Column, Round Slab, Footing, or Wall
2Enter dimensions in feet/inches or meters/cm
3Set the waste factor (default 10%) to account for spillage
4Click Calculate to see cubic yards, cubic meters, and bag counts (40/60/80 lb)
5Multi-area mode: add multiple sections (driveway + patio + walkway) for a combined total

Features

5 form types: Slab, Column, Round Slab, Footing, Wall
Metric and Imperial units
Cubic yards, cubic meters, ft³
40 lb, 60 lb, 80 lb bag counts
Adjustable waste factor (5–15%)
Multi-area mode with totals
100% browser-based

Concrete Calculator

How to Use

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