Short answer
A basic installed concrete slab costs about $10.63 to $13.00 per square foot (Homewyse, September 2026), including forms, reinforcement, pouring and finishing on a favorable site. The concrete alone costs $160–$195 or more per cubic yard. A 4-inch slab uses about 1.23 cubic yards per 100 square feet.
| Installed slab, basic (Sept 2026) | $10.63–$13.00 per sq ft[1] |
|---|---|
| Ready-mix concrete | $160–$195+ per cubic yard[2] |
| 2025 average ready-mix price | $179.95 per cubic yard[2] |
| Concrete in a 4-inch slab | ≈ 1.23 cu yd per 100 sq ft |
| Plain patio-style slab | $5–$8 per sq ft[3] |
| 80 lb bag yield (small jobs) | ≈ 0.60 cu ft[4] |
What a slab quote includes
Homewyse's basic slab figure covers laying out the pad height and slope, light grading, setting forms and reinforcement, and pouring and finishing the concrete, along with job supplies and equipment. It assumes favorable site conditions. Expect to pay more for:
- Excavation, removal of an old slab, or importing gravel base.
- Thicker slabs for vehicles or heavy loads (more concrete and rebar).
- Pump trucks when the ready-mix truck can't reach the pour.
- Permits and inspections, which are typical for foundations and structural slabs.
- General-contractor overhead if the slab is part of a larger project.
Cost per yard vs. cost per square foot
Ready-mix is priced per cubic yard: $160–$195 or more nationally, with a 2025 average of $179.95 according to ConcreteNetwork. That's only the material. Installed slabs are quoted per square foot because labor, forms and finishing usually cost more than the concrete itself. To turn your dimensions into yards and a cost range, use theconcrete calculator.
Slabs for foundations
Slabs that carry a building (garage, shop, ADU) are structural. They need footings or thickened edges, specified reinforcement and, in most places, a permit and inspection. Prices vary too much for a reliable national figure, so get quotes from licensed contractors who do foundation work.
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Frequently asked questions
How much does a 20×20 concrete slab cost?
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A 20 × 20 ft slab is 400 sq ft. At Homewyse's $10.63–$13.00 per sq ft basic installed rate that's about $4,250–$5,200. A 4-inch slab that size needs about 4.9 cubic yards, roughly $790–$960 of concrete at $160–$195 per yard.
How much concrete do I need for a slab?
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Multiply length × width × thickness, all in feet, and divide by 27 to get cubic yards. Add 5–10% for waste. A 4-inch (0.333 ft) slab needs about 1.23 cubic yards per 100 square feet.
Should I use bags or ready-mix for a slab?
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Bags make sense for small jobs. An 80 lb bag makes about 0.6 cu ft, so one cubic yard takes 45 bags. For anything over about a cubic yard, ready-mix delivered by truck is usually faster and more consistent.
Sources
- [1]Homewyse, Cost to Install Cement Slab (September 2026 figures)
- [2]ConcreteNetwork.com, Concrete Prices (updated July 14, 2026)
- [3]ConcreteNetwork.com, Concrete Patio Cost (updated January 20, 2026)
- [4]QUIKRETE, Concrete Mix No. 1101 data sheet (current product data)
Prices are national ranges published by the sources above, not quotes. Your price depends on size, access, site preparation and local labor rates. The only way to know is to compare written quotes.