12 by 10 ft slab at 8 inches
Calculate the requirements for a residential slab measuring 12 ft by 10 ft and 8 inches thick, reinforced with #4 bars at 18 inches apart. Ensure compliance with IRC R506.
Formula SSC-2026.1
Formula SSC-2026.1 · 4,000 PSI
Order volume
3.80 yd³
2.907 m³ placed+waste
Order weight
15,400 lb
6,985 kg
80 lb bags
172
5 pallets at 42 bags
60 lb bags
229
0.45 ft³ yield each
Rebar
262.00 ft
22 × 20 ft · 22 × 6 m · 193 lb
Ready-mix vs bags
$752.41
Truck $752.41 · 80 lb bags $1,161.00
Grid lines are equalized so the drawing stays readable. The order count uses on-center spacing with a bar at each end of the layout, then holds concrete cover in the field.
| Item | Net | Waste | Order | Unit price | Line total | Source Spec Material / Tool |
|---|---|---|---|---|---|---|
| Ready-mix concrete | 3.46 yd³ | 10% | 3.80 yd³ / 2.907 m³ | USD | $627.41 | Source Spec Material / Tool |
| Short-load fee | Under 4 yd³ | — | 1 truck @ 10 yd³ | USD | $125.00 | Source Spec Material / Tool |
| 80 lb pre-mix bags | 155.6 bags | 10% | 172 bags | USD | $1,161.00 | Source Spec Material / Tool |
| 60 lb pre-mix bags | 207.4 bags | 10% | 229 bags | USD | $1,236.60 | Source Spec Material / Tool |
| #4 rebar sticks, 20 ft | 22 sticks | 10% | 25 sticks / 22 × 6 m | USD | $350.00 | Source Spec Material / Tool |
| Rebar chairs | 63 crossings | 10% | 70 chairs | USD | $19.60 | Source Spec Material / Tool |
| Tie wire rolls | 63 ties | 10% | 1 rolls | USD | $8.00 | Source Spec Material / Tool |
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Ready-mix truck
$752.41
0.38 nominal 10 yd³ loads · 1 to order
80 lb bags
$1,161.00
60 lb alternative $1,236.60 · delivery weight 15,400 lb
| Thickness | Order yd³ | Order m³ | 80 lb bags | Rebar ft | Ready-mix | 80 lb cost |
|---|---|---|---|---|---|---|
| 4 in | 2.72 | 2.077 | 123 | 288 | $573.15 | $830.25 |
| 5 in | 2.99 | 2.284 | 135 | 288 | $617.96 | $911.25 |
| 6 in | 3.26 | 2.492 | 147 | 288 | $662.78 | $992.25 |
Show the deterministic formula
Slab ft³ = L × W × thickness ÷ 12. Thickened-edge extra = footing band × (footing depth − slab thickness), with corner squares counted once.
yd³ = ft³ ÷ 27. m³ = ft³ × 0.0283168. Weight uses 150 lb/ft³, then the header converts that pound total at 1 lb = 0.45359237 kg. 80 lb bags yield 0.6 ft³ and 60 lb bags yield 0.45 ft³. Currency changes the price labels only.
Bars across a span = floor(span ÷ spacing) + 1. Order sticks = that count, plus 10, 5, or 15 percent waste, cut from 20 ft and 6 m stock. Chairs = one per grid intersection.
Contractor sign-off
Project: 12 by 10 ft slab at 8 inches
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This sheet is an estimate for ordering and layout discussion. It is not a sealed design. Confirm the quantities with a licensed local professional and the authority having jurisdiction before you buy or build.
Engineering notes
This calculator is designed for a residential slab measuring 12 feet by 10 feet and 8 inches thick, utilizing #4 rebar spaced 18 inches apart. Please note that soil design considerations are excluded from this calculation.
For compliance, refer to the International Residential Code (IRC) R506, which outlines the requirements for concrete slabs in residential construction.
Code reference
IRC R506
Field questions
- What is the purpose of using #4 bars in the slab?
- The #4 bars are used to provide tensile strength to the concrete slab, helping to prevent cracking and improve structural integrity.
- Why is soil design excluded from this calculation?
- Soil design is excluded because it requires specific geotechnical analysis that varies by location and is beyond the scope of this slab calculator.
- What thickness is recommended for a residential slab?
- An 8-inch thickness is commonly recommended for residential slabs to ensure adequate strength and durability.
- How often should rebar be spaced in the slab?
- In this design, #4 bars are spaced 18 inches apart to provide sufficient reinforcement for the slab's load-bearing capacity.