Use this free concrete slab cost calculator to estimate the cost of pouring a residential concrete slab in 2026. Enter the slab dimensions and thickness, then adjust reinforcement, site preparation, finish, demolition and local cost level to create a preliminary project budget.
Concrete Slab Cost Calculator
Calculate square footage, concrete volume, cubic yards and estimated installation cost.
Estimated concrete slab cost
Planning estimate based on the dimensions and project options you selected.
This calculator provides a preliminary budgeting estimate. Slab design, thickness, reinforcement, base preparation and structural requirements should be determined for the specific project and local conditions.
How This Concrete Slab Cost Calculator Works
The calculator first multiplies slab length by width to determine square footage. Thickness is then used to calculate the actual volume of concrete required.
Because ready-mix concrete is commonly measured in cubic yards, the volume in cubic feet is divided by 27. The selected waste allowance is added only to the concrete quantity estimate.
Project cost is calculated separately using current installed concrete slab cost ranges. This avoids treating the cost of raw concrete as if it represented the entire professional installation.
Concrete Slab Cost in 2026
| Slab size | Typical installed cost |
|---|---|
| 10′ × 10′ — 100 sq. ft. | $600–$1,200 |
| 12′ × 12′ — 144 sq. ft. | $860–$1,700 |
| 20′ × 20′ — 400 sq. ft. | $2,400–$4,800 |
| 20′ × 30′ — 600 sq. ft. | $3,600–$7,200 |
| 30′ × 30′ — 900 sq. ft. | $5,400–$10,800 |
HomeGuide reports an average installed concrete slab price of about $6 to $12 per square foot in 2026. The actual cost varies with slab thickness, reinforcement, site conditions, finish and location.
How Many Cubic Yards of Concrete Do You Need?
To calculate concrete volume, multiply the slab length by its width and then by its thickness in feet. Divide the resulting cubic feet by 27 to convert the volume to cubic yards.
For example, a 20-by-20-foot slab that is 4 inches thick contains approximately 4.94 cubic yards of concrete before adding an allowance for waste.
With a 10% allowance, the estimated order quantity would be approximately 5.43 cubic yards.
What Changes Concrete Slab Cost?
Slab thickness
A thicker slab requires more concrete. Angi reports that residential patios are commonly about 4 to 6 inches thick, while heavier-duty projects such as driveways and foundations may require greater thickness depending on design requirements.
Site preparation
Concrete requires a stable base. Excavation, grading, compacted gravel and drainage work can increase the cost when the site is not already prepared.
Reinforcement
Rebar and fiber reinforcement can improve slab performance for appropriate applications. Angi reports an additional cost of roughly $0.50 to $1 per square foot for rebar and $2 to $3 per square foot for fiber mesh.
Concrete finish
A standard finish generally costs less than decorative treatments. Exposed aggregate, staining and stamping require additional materials and labor and can substantially increase the total project price.
Existing concrete removal
Replacing an existing slab requires demolition and disposal before the new pour. Concrete removal commonly costs about $2 to $6 per square foot, depending on thickness, reinforcement, accessibility and disposal requirements.
How Much Does a 20×20 Concrete Slab Cost?
A 20-by-20-foot slab contains 400 square feet. Using a typical installed range of $6 to $12 per square foot, a standard slab may cost approximately $2,400 to $4,800 before optional demolition, reinforcement or decorative finishes.
How Much Does a 30×30 Concrete Slab Cost?
A 30-by-30-foot slab contains 900 square feet. HomeGuide estimates approximately $5,400 to $10,800 for a slab of this size using its 2026 national installed cost range.
How Much Does Reinforcement Add?
Rebar reinforcement can add approximately $0.50 to $1 per square foot, while fiber mesh may add about $2 to $3 per square foot according to Angi’s 2026 cost data.
Whether reinforcement is required and what type should be used depends on the slab’s intended load, thickness, soil, climate and structural design.
What Is Included in This Estimate?
The base estimate represents a professionally installed residential concrete slab. The calculator separately adds reinforcement, decorative finish and existing-concrete demolition when those options are selected.
Site difficulty is treated as an estimating adjustment because excavation and grading requirements vary substantially between properties.
What Is Not Automatically Included?
Major excavation, engineered foundations, footings, drainage systems, retaining walls, utility relocation, concrete pumping, unusual access requirements, permits and structural engineering are not automatically included.
Foundation slabs for buildings may have substantially different structural and code requirements from patios, sidewalks or simple residential slabs.
Calculator Methodology
HomeFixLedger uses current U.S. installed concrete slab cost data as the baseline. HomeGuide reports approximately $6 to $12 per square foot installed in 2026, while Angi reports about $4 to $8 per square foot for typical slabs and higher costs for thicker or more complex structural applications.
The calculator uses a $6 to $12 per-square-foot baseline for a standard 4-inch residential slab. Thickness modifies this baseline moderately because thicker slabs require additional concrete but do not multiply every component of labor at the same rate.
Concrete volume is calculated independently using the actual slab dimensions and thickness. The waste allowance affects the displayed concrete order quantity but does not artificially multiply the entire installed project price.
Reinforcement, decorative finishes and existing concrete removal are treated as separate project components.
Last reviewed: September 2026
Frequently Asked Questions
How much does a concrete slab cost per square foot?
HomeGuide reports approximately $6 to $12 per square foot installed for a typical concrete slab in 2026. Angi reports approximately $4 to $8 per square foot for many standard slabs, with thicker and more complex structural projects costing more.
How many cubic yards are in a 20×20 slab?
A 20-by-20-foot slab that is 4 inches thick contains approximately 4.94 cubic yards of concrete before adding waste. At 6 inches thick, the same slab requires approximately 7.41 cubic yards.
How much concrete should I order?
The exact volume can be calculated from the slab dimensions, but contractors often allow extra material for variations in the base, spillage and other site conditions. This calculator lets you compare 5%, 10% and 15% allowances.
Is a 4-inch concrete slab thick enough?
Four inches is common for many residential applications, but it is not appropriate for every project. Vehicle loads, soil conditions, climate, reinforcement and structural requirements can change the required slab thickness.
Does this calculator include concrete removal?
Only when you select the existing-concrete removal option. The calculator then adds approximately $2 to $6 per square foot as a demolition and disposal allowance.