Skip to content
SlabCosts
Prices updated January 2026

40×40 Concrete Slab Cost

A 40×40 slab covers 1,600 square feet. Here's the concrete, bags and cost for 2026 — a common size for a shop / warehouse pad.

Concrete (4", waste in)

21.73 yd³

978 × 80 lb bags

Materials (ready-mix)

$2,716 – $4,128

delivered, 4" slab

Installed by a pro

$8,800 – $19,200

4" slab, national average

40×40 slab cost calculator

Adjust thickness, waste or region — the cost updates live.

Waste & region

Order extra for spillage & uneven subgrade. 10% is typical.

Installed cost estimate

$8,800 – $19,200

1,600 sq ft · 21.73 yd³ concrete

Bags of concrete needed (rounded up)

978

80 lb

1,304

60 lb

1,565

50 lb

1,956

40 lb

Ready-mix (delivered)
$2,716 – $4,128
Bagged mix (80 lb, DIY)
$5,379 – $8,802
Installed by a pro
$8,800 – $19,200

Estimate only — not a quote. Bag counts are rounded up and include a 10% waste allowance.

Installed $8,800 – $19,200

40×40 slab cost by thickness

Thickness Concrete 80 lb bags Ready-mix Installed
4" 21.73 yd³ 978 $2,716 – $4,128 $8,800 – $19,200
5" 27.16 yd³ 1,223 $3,395 – $5,161 $10,000 – $20,400
6" 32.59 yd³ 1,467 $4,074 – $6,193 $11,200 – $21,600

Includes a 10% waste allowance; bag counts rounded up. National US averages, January 2026.

You'll also need

Sized for this exact slab — tap any item to open its calculator with your measurements already filled in.

Gravel base

22.72 yd³

4" compacted base under the slab

≈ $681 – $1,477

Open calculator
Rebar

108 sticks

#4 bar, 18" grid (54 bars)

≈ $756 – $1,404

Open calculator
Bedding sand

4.94 yd³

~1" leveling layer

≈ $138 – $286

Open calculator

40×40 concrete slab: what to expect

A 40×40 slab covers 1,600 square feet. At the standard 4" thickness it takes about 21.73 cubic yards of concrete once you allow 10% for waste, which is roughly 978 × 80 lb bags if you mix by hand. Stepping up to 6" — sensible if it'll carry a vehicle — raises that to about 32.59 cubic yards.

Budget around $8,800 – $19,200 to have a 4" slab this size poured and finished by a contractor, or roughly $2,716 – $4,128 in ready-mix if you're doing the labor yourself. On top of the concrete you'll need about 22.72 yd³ of gravel base and 108 sticks of rebar.

Compare nearby sizes

Planning something bigger or smaller? Jump straight to the cost for a nearby size.

Size Concrete (4") 80 lb bags Installed cost
30×40 16.3 yd³ 734 $6,600 – $14,400
30×50 20.37 yd³ 917 $8,250 – $18,000
1,500 sq ft 20.37 yd³ 917 $8,250 – $18,000
30×60 24.44 yd³ 1,100 $9,900 – $21,600
40×50 27.16 yd³ 1,223 $11,000 – $24,000
40×60 32.59 yd³ 1,467 $13,200 – $28,800

See all common slab sizes →

Prices updated January 2026 National US averages · reviewed quarterly

Volumes use standard bag yields and a 10% waste allowance; costs are national US averages that vary by region, mix and finish. See our methodology for exactly how each figure is worked out, or check the reference sources:

Slab cost by project

Concrete Slab Cost Cost per sq ft + calculator Garage Slab Cost Typical 20×20 / 24×24 Driveway Slab Cost Concrete vs asphalt Patio Slab Cost 10×10 to 20×20 Shed Base Cost Small pads

Frequently asked questions

How much does a 40×40 concrete slab cost?
A 40×40 slab (1,600 sq ft) costs about $8,800 – $19,200 installed at 4" thick in 2026, or $11,200 – $21,600 at 6". DIY in materials, the ready-mix runs about $2,716 – $4,128 at 4".
How many yards of concrete for a 40×40 slab?
At 4" thick a 40×40 slab needs about 21.73 cubic yards including 10% waste (19.75 yd³ net). At 6" it needs about 32.59 cubic yards.
How many bags of concrete for a 40×40 slab?
At 4" you'd need roughly 978 × 80 lb bags, 1,304 × 60 lb bags or 1,956 × 40 lb bags. That's a lot of mixing — past about a cubic yard, ready-mix is usually cheaper and easier.
What base and rebar does a 40×40 slab need?
Plan on about 22.72 cubic yards of compacted gravel base and roughly 108 sticks of #4 rebar on an 18" grid. The "You'll also need" cards size these for you.