16 by 16 ft slab at 4 inches
Calculate the requirements for a 16 ft x 16 ft residential slab at 4 inches thick with #4 rebar at 18 inches. Compliant with IRC R506. Soil design is excluded.
Formula SSC-2026.1
Formula SSC-2026.1 · 4,000 PSI
Order volume
3.48 yd³
2.658 m³ placed+waste
Order weight
14,080 lb
6,387 kg
80 lb bags
157
4 pallets at 42 bags
60 lb bags
209
0.45 ft³ yield each
Rebar
352.00 ft
22 × 20 ft · 22 × 6 m · 259 lb
Ready-mix vs bags
$698.63
Truck $698.63 · 80 lb bags $1,059.75
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 | 3.16 yd³ | 10% | 3.48 yd³ / 2.658 m³ | USD | $573.63 | 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 | 142.2 bags | 10% | 157 bags | USD | $1,059.75 | Source Spec Material / Tool |
| 60 lb pre-mix bags | 189.6 bags | 10% | 209 bags | USD | $1,128.60 | 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
$698.63
0.35 nominal 10 yd³ loads · 1 to order
80 lb bags
$1,059.75
60 lb alternative $1,128.60 · delivery weight 14,080 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 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 is designed for a residential slab measuring 16 ft by 16 ft and 4 inches thick, reinforced with #4 bars placed at 18 inches on center. It is important to note that soil design considerations are excluded from this calculation.
Ensure compliance with the International Residential Code (IRC) R506 for slab-on-ground construction to maintain structural integrity and safety.
Code reference
IRC R506
Field questions
- What is the purpose of using #4 bars in the slab?
- The #4 bars provide reinforcement to the concrete slab, helping to control cracking and improve overall structural integrity.
- Why is soil design excluded from this calculation?
- Soil design is a separate consideration that involves analyzing the soil's bearing capacity and characteristics, which is beyond the scope of this slab design calculator.
- What thickness is recommended for a residential slab?
- A thickness of 4 inches is commonly recommended for residential slabs, providing a balance between strength and material use.
- How often should the rebar be placed in the slab?
- In this design, #4 bars should be placed at 18 inches on center to ensure adequate reinforcement throughout the slab.