12×24 Carport Slab, 5 Inch, 18 Inch Grid
A single-bay carport pad, 5 in thick, with an 18 in rebar grid.
Formula SSC-2026.1
Formula SSC-2026.1 · 3,500 PSI
Order volume
4.89 yd³
3.738 m³ placed+waste
Order weight
19,800 lb
8,981 kg
80 lb bags
220
6 pallets at 42 bags
60 lb bags
294
0.45 ft³ yield each
Rebar
420.00 ft
35 × 20 ft · 35 × 6 m · 309 lb
Ready-mix vs bags
$806.67
Truck $806.67 · 80 lb bags $1,485.00
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 |
|---|---|---|---|---|---|
| Ready-mix concrete | 4.44 yd³ | 10% | 4.89 yd³ / 3.738 m³ | USD | $806.67 |
| Short-load fee | Full load | — | 1 truck @ 10 yd³ | USD | $0.00 |
| 80 lb pre-mix bags | 200.0 bags | 10% | 220 bags | USD | $1,485.00 |
| 60 lb pre-mix bags | 266.7 bags | 10% | 294 bags | USD | $1,587.60 |
| #4 rebar sticks, 20 ft | 35 sticks | 10% | 39 sticks / 35 × 6 m | USD | $546.00 |
| Rebar chairs | 153 crossings | 10% | 169 chairs | USD | $47.32 |
| Tie wire rolls | 153 ties | 10% | 1 rolls | USD | $8.00 |
Ready-mix truck
$806.67
0.49 nominal 10 yd³ loads · 1 to order
80 lb bags
$1,485.00
60 lb alternative $1,587.60 · delivery weight 19,800 lb
| Thickness | Order yd³ | Order m³ | 80 lb bags | Rebar ft | Ready-mix | 80 lb cost |
|---|---|---|---|---|---|---|
| 4 in | 3.91 | 2.990 | 176 | 462 | $770.33 | $1,188.00 |
| 5 in | 4.89 | 3.738 | 220 | 462 | $806.67 | $1,485.00 |
| 6 in | 5.87 | 4.485 | 264 | 462 | $968.00 | $1,782.00 |
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: 12×24 Carport Slab, 5 Inch, 18 Inch Grid
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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
Twelve by twenty-four feet at 5 in is 4.44 cubic yards before waste. With 10 percent waste the order is about 4.89 yards, just above the 4 yard short-load hint, so check the plant minimum before you rely on the fee line. The grid is #4 at 18 in. Post bases and uplift anchors are not in the concrete volume.
Code reference
IRC R506.1 sets a 3.5 in minimum for concrete slab-on-ground floors. Reinforcement cover and spacing follow ACI 318 practice and the local inspector. This quantity takeoff is not a soils or structural design.
Field questions
- Does a carport slab include the post holes?
- No. This is the slab and optional thickened edge only. Augered post holes are a separate volume.
- What is the bag count if the truck minimum is too high?
- Read the 80 lb and 60 lb lines. They already include the waste factor and the bag yields of 0.60 and 0.45 cubic feet.
- Can I tighten the grid to 12 inches?
- Yes. Change spacing to 12, 16, 18, or 24 in. Bar count, chairs, and tie-wire rolls update together.