8 by 16 ft slab at 8 inches
Calculate the specifications for a residential slab measuring 8 ft by 16 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
4.07 yd³
3.115 m³ placed+waste
Order weight
16,500 lb
7,484 kg
80 lb bags
184
5 pallets at 42 bags
60 lb bags
245
0.45 ft³ yield each
Rebar
280.00 ft
23 × 20 ft · 23 × 6 m · 206 lb
Ready-mix vs bags
$672.22
Truck $672.22 · 80 lb bags $1,242.00
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 | 3.70 yd³ | 10% | 4.07 yd³ / 3.115 m³ | USD | $672.22 | Source Spec Material / Tool |
| Short-load fee | Full load | — | 1 truck @ 10 yd³ | USD | $0.00 | Source Spec Material / Tool |
| 80 lb pre-mix bags | 166.7 bags | 10% | 184 bags | USD | $1,242.00 | Source Spec Material / Tool |
| 60 lb pre-mix bags | 222.2 bags | 10% | 245 bags | USD | $1,323.00 | Source Spec Material / Tool |
| #4 rebar sticks, 20 ft | 23 sticks | 10% | 26 sticks / 23 × 6 m | USD | $364.00 | Source Spec Material / Tool |
| Rebar chairs | 66 crossings | 10% | 73 chairs | USD | $20.44 | Source Spec Material / Tool |
| Tie wire rolls | 66 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
$672.22
0.41 nominal 10 yd³ loads · 1 to order
80 lb bags
$1,242.00
60 lb alternative $1,323.00 · delivery weight 16,500 lb
| Thickness | Order yd³ | Order m³ | 80 lb bags | Rebar ft | Ready-mix | 80 lb cost |
|---|---|---|---|---|---|---|
| 4 in | 2.93 | 2.243 | 132 | 308 | $609.00 | $891.00 |
| 5 in | 3.22 | 2.461 | 145 | 308 | $656.06 | $978.75 |
| 6 in | 3.50 | 2.679 | 158 | 308 | $703.11 | $1,066.50 |
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: 8 by 16 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 helps you determine the necessary specifications for a residential concrete slab measuring 8 ft by 16 ft and 8 inches thick. The design incorporates #4 reinforcement bars spaced at 18 inches apart, ensuring structural integrity.
Please note that soil design considerations are excluded from this calculation. It is essential to consult with a qualified professional for soil analysis and site-specific requirements.
Code reference
IRC R506 - Concrete Floors on Ground
Field questions
- What is the purpose of using #4 bars in the slab?
- Using #4 bars helps to reinforce the concrete slab, providing additional tensile strength to resist cracking and improve overall durability.
- Why is soil design excluded from this calculation?
- Soil design is excluded because it requires site-specific analysis and considerations that vary based on local conditions. It's important to consult a professional for soil evaluation.
- What are the dimensions of the slab being calculated?
- The slab dimensions are 8 feet by 16 feet with a thickness of 8 inches.
- How often should the reinforcement bars be spaced?
- The #4 reinforcement bars should be spaced 18 inches apart within the slab.
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