Waste, bags and cost
Set to 0 to skip bag rounding.
Optional. No currency conversion is applied.
Result updated. Bags needed: 82 bags.
Result summary
Concrete estimate
Main project estimate from the values entered.
82 bags
Concrete volume is shown in cu yd; bag yield uses cu ft/bag.
Key numbers
- Volume with waste
- 1.358 cu yd
- Bags
- 82 bags
Key takeaway
This slab estimate needs about 1.358 cu yd after waste and rounds up to 82 bags.
Project details
Concrete details
- Base volume
- 1.235 cu yd
- Volume with waste
- 1.358 cu yd
- Bags
- 82 bags
- Estimated cost
- $492
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How this concrete calculator works
The calculator multiplies slab length, width and thickness to estimate base volume. US mode converts inches and cubic feet into cubic yards; metric mode converts millimetres into metres for cubic metres.
Assumptions
The estimate is for a simple rectangular slab. Waste allowance is applied after base volume, and bag count rounds up from the bag yield entered.
What this calculator does not include
This calculator does not design footings, reinforcement, forms, drainage, structural loads or code requirements. It is a general planning estimate, not building or engineering advice.
Key terms and assumptionsShort notes about slab scope, thickness, bag yield and estimate limits.
- Simple slab scope
- The calculator estimates rectangular slab volume only, not footings, reinforcement, forms or structural requirements.
- Thickness conversion
- US thickness is entered in inches and metric thickness in millimetres before volume is calculated.
- Bag yield
- Bag count uses the yield entered and rounds up to whole bags.
- General estimate
- Results are planning estimates only and are not building, engineering, supplier or cost-guarantee advice.
Guides and methodology
Plain-English notes that explain the assumptions behind related calculators and tools.
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FAQs
How do I calculate concrete for a slab?
Enter slab length, width and thickness. The calculator converts the thickness into the correct volume unit and adds the selected waste allowance.
What units does this support?
US mode uses feet for length and width, inches for thickness and cubic yards for volume. Metric mode uses metres, millimetres and cubic metres.
Can this estimate concrete bags?
Yes. Enter a bag yield and the calculator rounds up to whole bags. Set bag yield to 0 to skip bag rounding.
Does this cover footings or foundations?
No. This focused version estimates a simple slab volume and does not design footings, reinforcement, drainage or structural work.
Why include waste allowance?
Waste allowance helps cover spillage, uneven ground and measurement changes.
Is this a concrete supplier quote?
No. It is a general estimate from the values entered and not a quote or cost guarantee.