12 by 16 ft slab at 4 inches
Calculate the specifications for a residential slab measuring 12 ft by 16 ft at 4 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
276.00 ft
20 × 20 ft · 20 × 6 m · 203 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 | 20 sticks | 10% | 22 sticks / 20 × 6 m | USD | $308.00 | Source Spec Material / Tool |
| Rebar chairs | 99 crossings | 10% | 109 chairs | USD | $30.52 | Source Spec Material / Tool |
| Tie wire rolls | 99 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 | 2.61 | 1.994 | 118 | 304 | $555.22 | $796.50 |
| 5 in | 3.26 | 2.492 | 147 | 304 | $662.78 | $992.25 |
| 6 in | 3.91 | 2.990 | 176 | 304 | $770.33 | $1,188.00 |
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 16 ft slab at 4 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 specifications for a residential concrete slab measuring 12 ft by 16 ft with a thickness of 4 inches. The design includes #4 rebar spaced at 18 inches, ensuring structural integrity as per IRC R506 guidelines.
Please note that soil design considerations are excluded from this calculation. It is essential to conduct a proper soil assessment to ensure the suitability of the ground for the intended slab.
Code reference
IRC R506 - Concrete Floors on Ground
Field questions
- What is the purpose of using #4 bars in the slab?
- Using #4 bars provides reinforcement to the concrete slab, helping to control cracking and improve load-bearing capacity.
- Why is soil design excluded from this calculation?
- Soil design is excluded because it requires a separate assessment to determine the soil's bearing capacity and suitability for supporting the slab.
- What does IRC R506 cover?
- IRC R506 covers the requirements for concrete floors on ground, including design, construction, and reinforcement specifications.