Concrete Slab Cost Calculator
Get an instant free estimate for your concrete slab project.
How is Concrete Slab Cost Calculated?
The cost is primarily determined by Square Footage and Thickness (Volume). A 6-inch slab uses 50% more material than a 4-inch slab. Site preparation (grading, gravel) and specialized finishes (stamping) also add significantly to the price per square foot.
Calculate Your Estimate
Project Location
Choose which state the project is located.
Slab Dimensions
Enter the length and width of the area.
Slab Thickness:
Reinforcement:
Additional Services:
Key Factors Influencing Concrete Rates
Thickness & Mix
4-inch Slab: Standard for patios, sidewalks, and garage floors.
6-inch Slab: Required for heavy loads, such as driveways for large trucks or RV pads. Uses more cement and labor.
Finish Quality
Broom Finish: Standard non-slip texture. Lowest cost.
Stamped/Decorative: High-end aesthetic that mimics stone or tile. Expensive due to color hardeners, release agents, and detailed labor.
Average Cost by Size (4" Slab)
| Dimensions | Area (Sq Ft) | Estimated Cost Amount |
|---|---|---|
| 10' x 10' (Shed Base) | 100 sq ft | $800 – $1,200 |
| 12' x 24' (Patio/Patio) | 288 sq ft | $1,800 – $2,800 |
| 20' x 20' (2-Car Garage) | 400 sq ft | $2,400 – $3,500 |
| 24' x 24' (Large Garage) | 576 sq ft | $3,500 – $5,000 |
Additional Service Fees
| Service | Estimated Cost | Note |
|---|---|---|
| Concrete Pump | $500 – $800 | Daily rental flat rate |
| Slab Removal | $4 – $8 / sq ft | Breaking and hauling old concrete |
| Vapor Barrier | $0.50 / sq ft | 6-mil poly sheet |
| Grading | $1 – $2 / sq ft | Leveling the sub-base |
How to Estimate Concrete Slab Cost Manually
Calculating concrete costs involves determining the volume of wet cement needed and adding labor for prep and finishing.
Step 1: Calculate Area
Multiply Length × Width. Example: 24 ft × 24 ft = 576 sq ft.
Step 2: Determine Base Rate
4-inch Slab: ~$6 – $8 per sq ft installed.
6-inch Slab: ~$8 – $10 per sq ft installed (requires 50% more concrete).
Step 3: Add Reinforcement & Prep
Wire mesh adds ~$0.50/sq ft. Rebar adds ~$1.00/sq ft. Grading and gravel base can add $1-$2/sq ft.
Step 4: Apply Formula
(Sq_Ft × Base_Rate) + (Sq_Ft × Reinforcement) + Add-ons = Total
Example: 400 sq ft patio (4") with Rebar. (400 × $7) + (400 × $1) = $3,200.
Frequently Asked Questions
How long does a concrete slab take to dry?
Concrete takes 24-48 hours to dry enough to walk on, but 7 days to cure to ~70% strength, and 28 days to fully cure. You should not drive on a new driveway for at least 7-10 days.
Do I need 4 inches or 6 inches of concrete?
For patios, walkways, and shed bases, 4 inches is standard. For driveways that will hold heavy vehicles (RVs, trucks) or heavy machinery, 6 inches is recommended for durability.
Is rebar necessary for a 4-inch slab?
Rebar significantly strengthens concrete and prevents cracking. While wire mesh is cheaper and common for simple patios, rebar is highly recommended for driveways or any load-bearing slab.
What is a stamped concrete finish?
Stamped concrete is textured and colored to resemble stone, brick, slate, or wood. It is a premium finish that requires more labor and materials, typically costing $12-$18+ per sq ft.
Do I need a vapor barrier?
Yes, if the slab is for an indoor space (like a garage or basement) or if you plan to put flooring over it. It prevents ground moisture from seeping up through the porous concrete.
Does the weather affect installation?
Yes. Concrete cannot be poured in freezing temperatures (without expensive additives) or heavy rain. High heat can also cause it to cure too fast and crack, so early morning pours are common in summer.
What is the difference between specific PSI mixes?
PSI (Pounds per Square Inch) measures compressive strength. 3000 PSI is standard for residential slabs. 4000 PSI is used for heavy-duty driveways or commercial workshop floors.
Can I pour concrete over an existing slab?
It is possible but risky. The new layer must be bonded correctly, or it will crack and flake off. Usually, it is better to remove the old slab and pour a fresh, full-depth slab.
What permits are required?
Most cities require a permit for concrete work that alters impervious surface coverage (runoff) or touches the public right-of-way (like a driveway apron).
Does the price include a pump truck?
Usually, no. If the cement truck cannot reach the pour site (e.g., a backyard patio), a concrete pump is needed. This costs an extra $500-$800 per day.