10 by 8 ft slab at 5 inches
Calculate the specifications for a residential slab measuring 10 ft by 8 ft at 5 in thickness with #4 bars at 18 in spacing. Ensure compliance with IRC R506 standards.
Formula SSC-2026.1
Formula SSC-2026.1 · 4,000 PSI
Order volume
1.36 yd³
1.038 m³ placed+waste
Order weight
5,500 lb
2,495 kg
80 lb bags
62
2 pallets at 42 bags
60 lb bags
82
0.45 ft³ yield each
Rebar
116.00 ft
13 × 20 ft · 13 × 6 m · 85 lb
Ready-mix vs bags
$349.07
Truck $349.07 · 80 lb bags $418.50
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 | 1.23 yd³ | 10% | 1.36 yd³ / 1.038 m³ | USD | $224.07 | 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 | 55.6 bags | 10% | 62 bags | USD | $418.50 | Source Spec Material / Tool |
| 60 lb pre-mix bags | 74.1 bags | 10% | 82 bags | USD | $442.80 | Source Spec Material / Tool |
| #4 rebar sticks, 20 ft | 13 sticks | 10% | 15 sticks / 13 × 6 m | USD | $210.00 | Source Spec Material / Tool |
| Rebar chairs | 42 crossings | 10% | 47 chairs | USD | $13.16 | Source Spec Material / Tool |
| Tie wire rolls | 42 ties | 10% | 1 rolls | USD | $8.00 | Source Spec Material / Tool |
Source links open a product search on the Amazon storefront for the selected currency. SiteSpecCalc may earn a commission. The link does not change the quantities above.
Ready-mix truck
$349.07
0.14 nominal 10 yd³ loads · 1 to order
80 lb bags
$418.50
60 lb alternative $442.80 · delivery weight 5,500 lb
| Thickness | Order yd³ | Order m³ | 80 lb bags | Rebar ft | Ready-mix | 80 lb cost |
|---|---|---|---|---|---|---|
| 4 in | 1.09 | 0.831 | 49 | 128 | $304.26 | $330.75 |
| 5 in | 1.36 | 1.038 | 62 | 128 | $349.07 | $418.50 |
| 6 in | 1.63 | 1.246 | 74 | 128 | $393.89 | $499.50 |
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: 10 by 8 ft slab at 5 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 to assist in determining the specifications for a residential concrete slab. The slab dimensions are 10 ft by 8 ft with a thickness of 5 inches, reinforced with #4 bars spaced at 18 inches apart.
Please note that soil design considerations are excluded from this calculation. It is essential to consult a qualified engineer for soil analysis and other site-specific factors.
Code reference
IRC R506 - Concrete Floors on Ground
Field questions
- What is the purpose of using #4 bars in the slab?
- The #4 bars 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 site-specific analysis and varies based on local conditions. It's important to consult a professional for soil evaluation.
- What does IRC R506 cover?
- IRC R506 provides guidelines for the design and construction of concrete floors on the ground, including reinforcement requirements and installation practices.
- What are the dimensions of the slab being calculated?
- The slab dimensions are 10 feet by 8 feet with a thickness of 5 inches.