10 by 8 ft slab at 8 inches
Calculate the specifications for a residential slab measuring 10 ft by 8 ft at 8 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
2.61 yd³
1.994 m³ placed+waste
Order weight
10,560 lb
4,790 kg
80 lb bags
118
3 pallets at 42 bags
60 lb bags
157
0.45 ft³ yield each
Rebar
188.00 ft
17 × 20 ft · 17 × 6 m · 138 lb
Ready-mix vs bags
$555.22
Truck $555.22 · 80 lb bags $796.50
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 | 2.37 yd³ | 10% | 2.61 yd³ / 1.994 m³ | USD | $430.22 | 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 | 106.7 bags | 10% | 118 bags | USD | $796.50 | Source Spec Material / Tool |
| 60 lb pre-mix bags | 142.2 bags | 10% | 157 bags | USD | $847.80 | Source Spec Material / Tool |
| #4 rebar sticks, 20 ft | 17 sticks | 10% | 19 sticks / 17 × 6 m | USD | $266.00 | 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
$555.22
0.26 nominal 10 yd³ loads · 1 to order
80 lb bags
$796.50
60 lb alternative $847.80 · delivery weight 10,560 lb
| Thickness | Order yd³ | Order m³ | 80 lb bags | Rebar ft | Ready-mix | 80 lb cost |
|---|---|---|---|---|---|---|
| 4 in | 1.96 | 1.495 | 88 | 207 | $447.67 | $594.00 |
| 5 in | 2.12 | 1.620 | 96 | 207 | $474.56 | $648.00 |
| 6 in | 2.28 | 1.744 | 103 | 207 | $501.44 | $695.25 |
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.
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Project: 10 by 8 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 to assist in determining the specifications for a residential concrete slab measuring 10 feet by 8 feet and 8 inches thick. The design incorporates #4 rebar spaced 18 inches apart, adhering to the guidelines set forth in IRC R506.
Please note that soil design considerations are excluded from this calculation. It is essential to evaluate the soil conditions separately to ensure the structural integrity of the slab.
Code reference
IRC R506
Field questions
- What does IRC R506 cover?
- IRC R506 provides guidelines for the design and construction of concrete slabs on grade, including specifications for thickness, reinforcement, and placement.
- Why is soil design excluded?
- Soil design is excluded because it requires a separate analysis based on site-specific conditions, which can vary significantly and impact the slab's performance.
- What is the significance of using #4 bars at 18 in spacing?
- Using #4 bars at 18 inches spacing helps ensure adequate reinforcement of the slab, providing strength and stability to withstand loads and prevent cracking.
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