How much does a concrete slab cost per square foot?

A basic 4-inch concrete slab typically costs $4 to $8 per square foot installed in 2026. Thicker reinforced slabs for garages and shops run $6 to $12 per square foot depending on site prep and region.

How thick should a concrete slab be?

Patios and walkways: 4 inches. Driveways and garage floors: 4 to 5 inches. Shop floors, RV pads, and anything carrying heavy vehicles or equipment: 5 to 6 inches with rebar.

What PSI concrete should I use for a slab?

3,000 PSI is fine for patios and walkways. 3,500 to 4,000 PSI is the standard call for driveways, garage slabs, and exterior flatwork in freeze-thaw climates, ordered with air entrainment.

Guide 02 — Slab reference

Slab cost & thickness, sized right

Garage slabs, shop floors, shed pads, RV pads. What they cost per square foot, how thick they need to be for what you're parking on them, and the two or three spec words that separate a good pour from a cheap one.

Written by Steve Kuhbacher — 25+ years in heavy industrial construction and maintenance

Section 01 — Thickness by use

Fig. 1 — Slab thickness by duty (not to scale)

Cost per square foot

Table 1 — Installed slab cost ranges, 2026
Slab type	Spec	Typical $/sq ft
Shed / hot tub pad	4" · 3,000–3,500 PSI	$4 – $8
Patio	4" · broom finish	$6 – $12
Garage floor	4–5" · mesh or rebar	$5 – $10
Shop / pole barn floor	5–6" · rebar · 4,000 PSI	$6 – $12
RV / parking pad	5–6" · rebar	$6 – $11

Small jobs carry a small-job premium: a crew mobilizes the same trucks and screeds for a 120 sq ft shed pad as for a 600 sq ft driveway, so don't be surprised when tiny pours cost more per foot.

Section 02 — Spec words that matter

The plain-English spec sheet

PSI (strength). 3,000 PSI covers patios and walkways. 3,500–4,000 PSI is the right call for anything vehicles touch. The cost difference per yard is small; the durability difference isn't.
Air entrainment. Microscopic air bubbles that give freezing water somewhere to go. Non-negotiable for exterior concrete in freeze-thaw climates. If your contractor doesn't mention it in a northern state, ask why.
Reinforcement. Wire mesh helps hold cracks tight; rebar adds real structural capacity. Thicker slab + rebar is the spec when trucks, campers, or equipment park on it.
Control joints. Concrete cracks — the joints decide where. Sawcut or tooled joints at roughly 2.5–3× the slab thickness in feet (a 4" slab gets joints every 10–12 ft). No joints in the quote is a red flag.
Cure time. Foot traffic in 24–48 hours, passenger cars in about 7 days, heavy vehicles at 28 days when concrete reaches design strength. A crew that says "drive on it tomorrow" is telling you something.

Quick math Cubic yards = length × width × thickness (ft) ÷ 27. A 24 × 30 shop floor at 6 inches is 13.3 yards — order 14 to 15. At $130–$180/yard, material alone is roughly $1,900–$2,700 before labor, base, and forming.

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