Concrete slab cost per square foot
A plain 4-inch broom-finished slab runs about $5–$9 per sq ft installed — forms, a compacted gravel base, concrete, placing and finishing. Upgrades add:
| Option | Adds per sq ft |
|---|---|
| Each extra inch of thickness | $0.60–$1.00 |
| Colored finish | $1–$3 |
| Exposed aggregate finish | $2–$4 |
| Stamped finish | $6–$12 |
| Wire mesh | $0.20–$0.50 |
| Rebar grid | $0.50–$1.25 |
| Break out and haul away an old slab | $2–$6 |
Cost of common slab sizes
| Slab | Size | Thickness | Concrete | Installed (broom, mesh) |
|---|---|---|---|---|
| Shed pad | 10 × 12 ft | 4" | 1.6 yd³ | $624–$1,140 |
| Patio | 12 × 16 ft | 4" | 2.6 yd³ | $998–$1,824 |
| Patio | 20 × 20 ft | 4" | 5.4 yd³ | $2,080–$3,800 |
| One-car garage | 12 × 24 ft | 5" | 4.9 yd³ | $1,670–$3,024 |
| Two-car garage | 24 × 24 ft | 5" | 9.8 yd³ | $3,341–$6,048 |
| Workshop | 30 × 40 ft | 6" | 24.4 yd³ | $7,680–$13,800 |
DIY vs. hiring a contractor
Concrete itself is only a third to half of the installed price. Ready-mix costs about $130–$200 per cubic yard in 2026, plus delivery and short-load fees for small orders; an 80 lb bag is $5–$8. DIY saves the labor on small pads and walkways, but slabs over about 100 sq ft need several helpers, a power screed or bull float, and perfect timing — a bad pour is expensive to remove.
Need just the volume? Use the concrete calculator.
FAQ
How much does a 20 × 20 concrete slab cost?
About $2,100–$3,800 for a 4" broom-finished slab with mesh (400 sq ft at $5.20–$9.50), more if stamped or colored.
How thick should a garage slab be?
4" is the common minimum; 5–6" with rebar is better for heavy trucks, workshops and lifts.
Is stamped concrete worth it?
It roughly doubles the cost of a patio ($12–$20 per sq ft) but looks like stone or pavers for less than real pavers. It needs resealing every 2–3 years.