16 by 16 ft slab at 5 inches
Calculate the requirements for a 16 ft by 16 ft residential slab at 5 inches thick with #4 rebar at 18 inches spacing. Compliant with IRC R506. Soil design considerations are excluded.
Formula SSC-2026.1
Formula SSC-2026.1 · 4,000 PSI
Order volume
4.35 yd³
3.323 m³ placed+waste
Order weight
17,600 lb
7,983 kg
80 lb bags
196
5 pallets at 42 bags
60 lb bags
261
0.45 ft³ yield each
Rebar
352.00 ft
22 × 20 ft · 22 × 6 m · 259 lb
Ready-mix vs bags
$717.04
Truck $717.04 · 80 lb bags $1,323.00
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 | 3.95 yd³ | 10% | 4.35 yd³ / 3.323 m³ | USD | $717.04 | 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 | 177.8 bags | 10% | 196 bags | USD | $1,323.00 | Source Spec Material / Tool |
| 60 lb pre-mix bags | 237.0 bags | 10% | 261 bags | USD | $1,409.40 | 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 | 121 crossings | 10% | 134 chairs | USD | $37.52 | Source Spec Material / Tool |
| Tie wire rolls | 121 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
$717.04
0.43 nominal 10 yd³ loads · 1 to order
80 lb bags
$1,323.00
60 lb alternative $1,409.40 · delivery weight 17,600 lb
| Thickness | Order yd³ | Order m³ | 80 lb bags | Rebar ft | Ready-mix | 80 lb cost |
|---|---|---|---|---|---|---|
| 4 in | 3.48 | 2.658 | 157 | 387 | $698.63 | $1,059.75 |
| 5 in | 4.35 | 3.323 | 196 | 387 | $717.04 | $1,323.00 |
| 6 in | 5.21 | 3.987 | 235 | 387 | $860.44 | $1,586.25 |
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: 16 by 16 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 assists in determining the specifications for a residential concrete slab measuring 16 ft by 16 ft and 5 inches thick. The slab incorporates #4 rebar placed at 18-inch intervals to enhance structural integrity.
Note that soil design considerations are excluded from this calculation, and it is essential to consult local building codes and a qualified professional for site-specific requirements.
Code reference
IRC R506 - Concrete Floors on Ground
Field questions
- What is the purpose of using #4 rebar in the slab?
- The #4 rebar is used to reinforce the concrete slab, providing additional strength and helping to prevent cracking.
- Why is soil design excluded from this calculation?
- Soil design is excluded because it requires site-specific analysis and should be conducted by a qualified professional to ensure proper load-bearing capacity.
- What thickness is recommended for a residential slab?
- A thickness of 5 inches is commonly recommended for residential slabs, but this may vary based on specific load requirements and local building codes.
- How do I ensure compliance with IRC R506?
- To ensure compliance with IRC R506, follow the guidelines for concrete mix, reinforcement, and placement as outlined in the code, and consult a professional for site-specific conditions.
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