14 by 30 ft slab at 4 inches
Calculate the requirements for a residential slab measuring 14 ft by 30 ft with a thickness of 4 inches and #4 bars spaced at 18 inches. Compliance with IRC R506 is noted, excluding soil design considerations.
Formula SSC-2026.1
Formula SSC-2026.1 · 4,000 PSI
Order volume
5.70 yd³
4.361 m³ placed+waste
Order weight
23,100 lb
10,478 kg
80 lb bags
257
7 pallets at 42 bags
60 lb bags
343
0.45 ft³ yield each
Rebar
594.00 ft
41 × 20 ft · 41 × 6 m · 436 lb
Ready-mix vs bags
$941.11
Truck $941.11 · 80 lb bags $1,734.75
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 | 5.19 yd³ | 10% | 5.70 yd³ / 4.361 m³ | USD | $941.11 | 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 | 233.3 bags | 10% | 257 bags | USD | $1,734.75 | Source Spec Material / Tool |
| 60 lb pre-mix bags | 311.1 bags | 10% | 343 bags | USD | $1,852.20 | Source Spec Material / Tool |
| #4 rebar sticks, 20 ft | 41 sticks | 10% | 46 sticks / 41 × 6 m | USD | $644.00 | Source Spec Material / Tool |
| Rebar chairs | 210 crossings | 10% | 231 chairs | USD | $64.68 | Source Spec Material / Tool |
| Tie wire rolls | 210 ties | 10% | 1 rolls | USD | $8.00 | Source Spec Material / Tool |
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Ready-mix truck
$941.11
0.57 nominal 10 yd³ loads · 1 to order
80 lb bags
$1,734.75
60 lb alternative $1,852.20 · delivery weight 23,100 lb
| Thickness | Order yd³ | Order m³ | 80 lb bags | Rebar ft | Ready-mix | 80 lb cost |
|---|---|---|---|---|---|---|
| 4 in | 5.70 | 4.361 | 257 | 653 | $941.11 | $1,734.75 |
| 5 in | 7.13 | 5.451 | 321 | 653 | $1,176.39 | $2,166.75 |
| 6 in | 8.56 | 6.541 | 385 | 653 | $1,411.67 | $2,598.75 |
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: 14 by 30 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 14 feet by 30 feet with a thickness of 4 inches. The reinforcement consists of #4 bars placed at 18-inch intervals, ensuring structural integrity.
It is important to note that this design adheres to the guidelines set forth in IRC R506, but does not include soil design considerations. Always consult a licensed engineer for site-specific requirements.
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 load-bearing capacity.
- Why is soil design excluded from this calculation?
- Soil design is site-specific and depends on various factors such as soil type and load conditions, which are not covered in this general slab design calculator.
- What is the significance of adhering to IRC R506?
- IRC R506 provides guidelines for the construction of concrete slabs, ensuring safety and structural integrity in residential applications.