Concrete calculator
Calculate concrete for a slab, footing or round column and the materials to mix it on site.
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How it is calculated
Slab: V = length × width × thickness Column: V = π × D² / 4 × height
1 yd³ = 27 ft³ = 0.765 m³
Indicative mix per m³: structural concrete with about 350 kg of cement, 700 kg of sand, 1100 kg of gravel and 180 L of water.
Add 5–10 % for uneven ground and spillage.
Frequently asked questions
How much concrete for a 16 × 13 ft slab, 4 in thick?
About 2.6 yd³ (2 m³) before waste, or 2.7 yd³ with 5 % extra.
How many bags of cement per cubic yard?
For structural concrete, about 6 bags of 94 lb (roughly 270 kg per yd³).