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.
Example
You enter
- Length (ft) 4
- Width (ft) 4
- Thickness (in) 4
- Bag yield (ft³): 80lb 0.60, 60lb 0.45, 50lb 0.375, 40lb 0.30 0.6
- Waste (percent) 10
You get
- Pour volume 5.33 ft^3
- Bags needed 10
Details, formula, and sources
Where ready-mix by the yard makes no sense. 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.
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.
The takeoff is public first-principles (pour volume over the per-bag yield); the per-bag yield is printed on every bag of concrete.
Estimate. AHJ and licensed professional govern.
Field names used by the API: length_ft, width_ft, thickness_in, bag_yield_ft3, waste_pct, volume_ft3, bags
- Volume over bag yield volume = L x W x (thickness_in/12); bags = ceil(volume x (1 + waste) / bag yield); round upmaterial-takeoff practice
- Bag yields ~0.0075 ft^3/lb: 80 lb ~0.60, 60 lb ~0.45, 50 lb ~0.375, 40 lb ~0.30; past ~1 cu yd (~45 of the 80 lb bags) use ready-mixmanufacturer bag yield (Quikrete / Sakrete)