Concrete Calculator
Volume and bag count for a slab, footing or post hole.
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How it works
Volume = length × width × depth. A 20 kg bag of ready-mix yields ≈ 0.01 m³; a 25 kg bag ≈ 0.0125 m³; a 40 kg bag ≈ 0.02 m³ (check your brand — yields vary).