Bag count starts with published yield
A bag label is a weight, not a volume. This takeoff converts slab geometry to cubic feet, then uses the manufacturer’s published yield for the selected bag. That keeps the arithmetic auditable and the final partial bag rounded up.
The base is part of the takeoff
The default compacted gravel depth is 3 in, the lower end of QUIKRETE’s 3–4 in slab-guide range. Gravel stays in cubic feet until a bag with a published volume is selected.
Structural choices stay open
A patio, driveway and equipment pad can share dimensions and require different reinforcement. The list names that missing decision instead of inventing a mesh or rebar schedule from geometry alone.
Questions before the pour
How many concrete bags do I need for a slab?
The calculator multiplies slab length, width and thickness for net volume, then divides by QUIKRETE's published yield: 0.60 cubic feet for an 80 lb bag or 0.45 cubic feet for a 60 lb bag. The final bag count always rounds up.
Does the calculator automatically add waste?
No. The cited manufacturer data does not prescribe one universal allowance, so the default is zero rather than a hidden guess. You can add an explicit percentage for uneven excavation or spillage.
Does this tell me what reinforcement to use?
No. Dimensions alone do not reveal loads, soil, exposure or local rules. Reinforcement stays marked for confirmation unless you explicitly choose a fiber-reinforced bagged mix.
Can I see the complete result without entering an email?
Yes. Concrete, base, forms, joints and finish items appear first. Sending or printing the list is optional and appears only after the complete result.