How much does a concrete slab cost in 2026?
A standard 4-inch residential concrete slab costs $6 to $12 per square foot installed in most U.S. markets in 2026, with the national average sitting near $8 per square foot. Price varies meaningfully with thickness, reinforcement, finish, site conditions, and your state — which is why the calculator above gives a range rather than a single number.
For quick reference, here is what typical residential slab projects cost installed by a contractor in 2026:
| Project | Typical size | Installed cost (range) |
|---|
| Patio | 10×10 (100 sq ft) | $700 – $1,400 |
| Shed pad | 12×16 (192 sq ft) | $1,300 – $2,500 |
| Garage slab | 20×20 (400 sq ft) | $3,400 – $6,400 |
| Driveway | 16×40 (640 sq ft) | $5,800 – $10,500 |
| Shop slab | 30×40 (1,200 sq ft) | $13,000 – $26,000 |
Materials alone (DIY mode in the calculator) usually run $3 to $7 per square foot. Hiring a contractor adds labor (typically $2–$3/sq ft) plus a 20–35% overhead and profit markup. The total is what most homeowners pay.
What drives concrete slab cost
- Slab area — the single biggest factor.
- Thickness — a 6″ slab uses 50% more concrete than a 4″ slab.
- Reinforcement — rebar adds $0.60–$1.05/lf; mesh runs $0.30–$0.85/sq ft.
- Site prep — difficult sites with grading or rocky soil can add $4–$9/sq ft.
- Finish — broom is standard; stamped/decorative concrete adds $8–$16/sq ft installed.
- Access — pump trucks add $700–$1,800; wheelbarrow access adds significant labor.
- Region — California and New York labor can run 30–40% above national average.
How to calculate concrete for a slab
Concrete is sold in cubic yards. To figure out how much you need:
- Multiply length × width × thickness, with thickness converted to feet (divide inches by 12).
- That gives volume in cubic feet.
- Divide by 27 to convert to cubic yards.
- Add a 10% waste factor (15% for irregular forms).
Worked example: a 20 ft × 20 ft × 4″ garage slab is 20 × 20 × (4/12) = 133.3 cu ft, or 133.3 ÷ 27 = 4.94 cubic yards. Add 10% waste → order 5.5 cubic yards.
For pours under 1 cubic yard, bagged concrete is usually cheaper than ready-mix delivery — short-load fees can add $100–$250 to a small order. The calculator switches automatically based on slab size.
How thick should my concrete slab be?
- 3.5–4 inches — patios, walkways, sidewalks, shed pads.
- 5–6 inches — driveways, garages, RV pads.
- 6–8 inches — workshop slabs, equipment pads.
- 8+ inches — heavy commercial, structural — talk to an engineer.
DIY vs hiring a contractor
Pouring your own slab is feasible for projects under ~150 square feet. Beyond that, the workflow demands more hands than most weekend DIYers have — concrete sets in 60–90 minutes once it hits the forms.
What you save going DIY
You skip labor and contractor markup. For a 10×10 patio, that is roughly $300–$700 in savings. For a 20×20 garage slab, savings can hit $2,000–$3,500 — but only if you have the crew, tools, and experience.
What can go wrong DIY
- Cold joints if the pour stalls past 60–90 minutes.
- Surface scaling if finishing is rushed.
- Cracking from missing or under-spaced control joints.
- Settlement from undercompacted base.
Frequently asked questions
How much does a concrete slab cost in 2026?
A standard 4-inch residential slab costs $6–$12/sq ft installed in most US markets in 2026, with the national average around $8/sq ft. A 10×10 patio runs $700–$1,400 installed. A 20×20 garage slab runs $3,400–$6,400 installed.
How do I calculate cubic yards of concrete?
Multiply length (ft) × width (ft) × thickness (ft, so divide inches by 12). That gives cubic feet. Divide by 27 for cubic yards. Add a 10% waste factor.
Is a 4-inch concrete slab thick enough?
A 4-inch slab is correct for patios, walkways, and shed pads. Driveways and garages typically need 6 inches. Shop slabs and structural slabs need 6–8 inches and may require engineering.
Should I use rebar or wire mesh?
Wire mesh is fine for patios and shed pads. Rebar (#4 at 16″ O.C.) is recommended for driveways, garages, and any slab with vehicle loads. Both control cracks dramatically better than no reinforcement.
How much do contractors mark up?
Most concrete contractors apply 20–35% overhead and profit on top of materials and labor. The Contractor Installed mode includes this markup band; DIY Materials mode excludes it.
Why does the calculator show a price range?
Material and labor costs vary 20–50% across US regions, suppliers, and seasons. A range gives an honest planning estimate. Use the low end as a best-case bid; use the high end as a realistic ceiling.
What is a thickened edge and do I need one?
A thickened edge (turndown) is where the slab perimeter is poured deeper, typically 12″ wide and 12–18″ deep. Required for slabs that act as their own footing — garage slabs, slab-on-grade foundations. Patios and shed pads usually don't need one.
Do I need a permit?
It depends on your jurisdiction and slab use. Patios are often unpermitted; driveways usually require one ($50–$300); garage slabs and foundation slabs almost always require permits ($150–$1,500+). Check with your local building department.
About this calculator
T
Takeoff editorial team
Construction estimating tools, updated quarterly. Sources cited in the methodology panel above.