40x50 Concrete Slab, 4 Inches Thick
Poured 4 in thick, a 40 × 50 ft slab covering 2,000 sq ft needs about 27.16 cubic yards of concrete once 10% is added for waste. For ready-mix, order 27.25 cu yd for the 40x50, about $3,815 – $4,905 delivered. Bagged, the same 40x50 is 1,223 80 lb or 1,630 60 lb bags, about $8,150 – $11,410 for the concrete alone.
- Ready-mix order
- 27.25 cu yd
- Ready-mix cost
- $3,815 – $4,905
- 80 lb bags
- 1,223
- Bag cost
- $8,150 – $11,410
Materials only for a 40x50 at 4 in, from national price ranges as of 2026-09; not a live quote.
What a 40x50 slab handles
A 40x50 is a two-thousand-square-foot shop: room for an RV bay, two vehicle bays and a workshop, or an equipment barn on a small farm.
A pour this size is commonly placed in sections, with construction joints planned at door lines or bay lines.
Most buildings this big also have plumbing, so the drains and supply lines go in before the base, and the building department may want to see them before the pour.
Before you pour the 40x50 at 4 in
- Schedule the under-slab plumbing inspection before the pour date.
- Decide the pour sections and where the construction joints fall.
- For trucks and tractors, consider 5 to 6 in in the drive lanes.
Full plan for a 40x50 slab, 4 in
- Area
- 2,000 sq ft
- Thickness
- 4 in
- Volume
- 27.16 cu yd
Bagged concrete estimate (DIY)
$10,087 – $14,563
Est. as of 2026-09 — not a live quote
Ready-mix delivered (materials only)
$3,815 – $4,905
Est. as of 2026-09 — not a live quote
For a pour this size, ready-mix delivery is typically more practical than mixing bags by hand.
Shopping list
- Concrete mix (60 lb bags) Or 2,445 × 40 lb, 1,956 × 50 lb or 1,223 × 80 lb bags. 1,630 bags
- Ready-mix concrete Alternative to bagged mix; most suppliers have a 1 cu yd order minimum. 27.25 cu yd
- Compactable gravel sub-base 4 in compacted base beneath the slab. 33.33 tons
- 6x6 welded wire mesh Reinforcement for crack control; not a substitute for engineered rebar on structural slabs. 2,200 sq ft
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Buy bagged concrete
Pick up bagged mix and reinforcement from a hardware store for smaller pours.
View shopping listAssumptions
- Waste allowance: 10% applied to account for over-excavation and spillage.
- Approx. wet weight: 110,000 lb (55 tons).
- Prices are national-average retail/delivery ranges as of 2026-09, not live quotes.
Bags or ready-mix for a 40x50 slab, 4 in?
The 40x50 at 4 in needs 4 trucks: 27.25 cu yd at 8 cu yd a load, the low end of what a truck carries, for about $3,815 – $4,905. Ask the supplier to space the trucks so each load goes down before the last one stiffens (a wet edge), line up enough hands to place and finish 2,000 sq ft at 4 in, and ask about a pump if the truck can't reach every corner of the 40x50. On the 40x50, ready-mix comes out cheaper by about $5,420 at the middle of each range, and it saves mixing 1,223 bags.
Is 4 in thick enough for a 40x50 slab?
For a 40x50 garage or shop floor that carries passenger cars, 4 in is common and above the IRC minimum of 3-1/2 in. Go to 5 or 6 in if the 40x50 will hold heavy pickups, an RV, a car lift or a tractor, or sits on soft or clay soil, and check your local code first. At 6 in the same 40x50 takes about 40.74 cu yd.
Control joints for a 40x50 slab at 4 in
Like any slab, a 4 in 40x50 shrinks while it cures; control joints decide where its cracks go. The usual rule (ACI and PCA guidance) puts joints in a 40x50 at 4 in every 8 to 12 ft, 24 to 36 times the thickness, cut 1 in deep (a quarter of the thickness) as soon as the surface takes the saw without raveling, usually within the first day.
On the 40x50 at 4 in, a joint every 10 ft or less means 4 joints across the 50 ft side and 3 joints across the 40 ft side: 20 panels of about 10 × 10 ft and 310 ft of saw cut.
How much a 40x50 slab 4 in thick weighs
At roughly 150 lb per cubic foot of wet concrete, a 40x50 at 4 in puts about 110,000 lb (55 tons) on the ground. As bags, the 40x50 is 1,223 80 lb bags, 97,840 lb in all: about 66 trips in a pickup carrying 1,500 lb a load. Nobody hauls 97,840 lb of bags for a 40x50 in a pickup; it comes by ready-mix truck or as pallets on a delivery truck.
The 40x50 at 4 in against nearby sizes
Every row uses the same 10% waste and prices as the 40x50 at 4 in; costs are for the concrete only.
| Slab | Cu yd | 60 lb bags | 80 lb bags | Ready-mix order | Bags cost | Ready-mix cost |
|---|---|---|---|---|---|---|
| 30x60 slab, 4 in | 24.44 | 1,467 | 1,100 | 24.5 cu yd | $7,335 – $10,269 | $3,430 – $4,410 |
| 40x50 slab, 4 in (this page) | 27.16 | 1,630 | 1,223 | 27.25 cu yd | $8,150 – $11,410 | $3,815 – $4,905 |
| 40x60 slab, 4 in | 32.59 | 1,956 | 1,467 | 32.75 cu yd | $9,780 – $13,692 | $4,585 – $5,895 |
Questions about a 40x50 slab, 4 in
How many bags of concrete for a 40x50 slab 4 inches thick?
Plan on 733.3 cubic feet for the 40x50, which is 1,223 80 lb bags, 1,630 60 lb bags, 1,956 50 lb or 2,445 40 lb bags once 10% waste is in.
How many yards of concrete for a 40x50 slab 4 inches thick?
The 40x50 measures out at 24.69 cubic yards, or 27.16 with 10% for waste. Order 27.25 cu yd for the 40x50, since ready-mix is sold in quarter yards with a 1 yard minimum at most plants.
How much does a 40x50 concrete slab 4 inches thick cost?
Concrete alone for the 40x50 runs about $3,815 – $4,905 for 27.25 cu yd of ready-mix delivered, or $8,150 – $11,410 for 1,630 60 lb bags. Add a 4 in gravel base and wire mesh and the bagged 40x50 plan comes to $10,087 – $14,563. Labor, forms and finishing for a 40x50 at 4 in come on top of these national ranges (as of 2026-09), which are not quotes.
How much does a 40x50 concrete slab 4 inches thick weigh?
About 110,000 lb (55 tons) of wet concrete for the 40x50, at 150 lb per cubic foot. The 1,223 80 lb bags for a 40x50 weigh 97,840 lb: about 66 trips in a pickup carrying 1,500 lb a load.
Where do control joints go on a 40x50 slab 4 inches thick?
On a 40x50 at 4 in, every 8 to 12 ft (24 to 36 times the thickness), sawn 1 in deep. On the 40x50 at 4 in, a joint every 10 ft or less means 4 joints across the 50 ft side and 3 joints across the 40 ft side: 20 panels of about 10 × 10 ft and 310 ft of saw cut.
Limitations
The 40x50 figures at 4 in are material estimates and typical price ranges, not a quote or a structural design. Confirm that 4 in, the reinforcement and the joint layout suit your soil, loads and local code for a 40x50 slab with a qualified professional.