Bagged Concrete Count for a Small Pour
The bags of pre-mixed concrete for a small rectangular pour -- a pad, footing, curb, or equipment base -- where ready-mix by the yard makes no sense (the complement of post-hole-concrete's cylinder case, and the concrete tile's cubic-yard/ready-mix output). Volume = L x W x (thickness_in/12); bags = ceil(volume x (1 + waste) / bag yield). Bag yield ~0.0075 ft^3/lb: an 80 lb bag ~0.60 ft^3, 60 lb ~0.45, 50 lb ~0.375, 40 lb ~0.30. A 4 x 4 ft pad, 4 in thick = 5.33 ft^3, so at 10% waste it takes 10 of the 80 lb bags or 14 of the 60 lb. Round up (a partial bag opens a whole one) and add for uneven subgrade and spillage; past ~1 cu yd (~45 of the 80 lb bags) ready-mix is cheaper. A material-ordering estimate; the printed bag yield, the real formwork, and the mix design govern.
Formula and source
volume_ft3 = length_ft x width_ft x (thickness_in / 12); bags = ceil(volume_ft3 x (1 + waste_pct/100) / bag_yield_ft3). Bag yield ~0.0075 ft^3/lb: 80 lb ~0.60, 60 lb ~0.45, 50 lb ~0.375, 40 lb ~0.30.
Bagged concrete count for a small pour (manufacturer bag yield; Quikrete / Sakrete published yields), by name; the printed bag yield, the real formwork dimensions, and the mix design govern.
Audience
This tile is built for trades and the adjacent professions in the Carpentry and Construction group. The interactive calculator runs entirely in your browser. No account, no fee, no advertising, no tracking.
Related tools
Posture
Rough Logic answers the math question the working professional asks on the job. The site is a calm, fast, ad-free, account-free, ever-free reference. It does not interpret code. It does not replace the licensed professional. It does not store your inputs. The Authority Having Jurisdiction governs all installations and inspections.