Concrete Bags Calculator

Enter the dimensions of your slab, footing, or post hole. We'll estimate how many bags you need — for 80 lb, 60 lb, and 50 lb bags — rounded up to the next whole bag, plus one spare.

Length (ft) Width (ft) Thickness (in) e.g. 4″ for a slab, or the depth of a footing/post hole.

Volume ÷ bag yield, rounded up, plus 1 spare bag — the same rule Buildholm's own build plans use. Yields: 80 lb ≈ 0.60 ft³; 60 lb ≈ 0.45 ft³; 50 lb ≈ 0.375 ft³. Prices are a national estimate (lowest of Home Depot, Lowe's, ACE Hardware) — actual prices vary by store, date, and ZIP.

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