Concrete Slab Cost Calculator
Reviewed by Engr. Talha Tariq | PEC License #: PEC-CIVIL-37815 | Last updated: 2026-02-22
Our Concrete Slab Cost Calculator helps you estimate the total financial layout for your next pour. Whether it's a small backyard patio or a full garage slab, compare Ready-Mix and Bagged costs, factor in local labor rates, and account for reinforcement extras.
Estimate material and labor costs for your concrete slab project.
Total cost = (Volume × Concrete Price) + (Area × Labor Rate) + (Area × Extra Rate).
Enter your dimensions and costs above to see your project estimate.
Complete Guide to Concrete Slab Costs
Estimate not just the volume, but the total financial layout including professional installation and ready-mix delivery.
Compare costs between ordering a concrete truck or mixing it yourself using standard 80lb bags for smaller projects.
Account for rebar, wire mesh, or vapor barriers by adding extra costs per square foot to your estimate.
Customize your estimate with local labor rates and material prices to match your specific ZIP code market.
Built-in 10-15% overrun calculator ensures you don't run dry during the pour due to spillage or uneven subgrade.
Generate a clean, printable summary of your project inputs and costs to share with contractors or keep for records.
Why Use Our Concrete Slab Cost Calculator?
- Accurate financial planning for patios, driveways, garage floors, and shed bases.
- Avoid "sticker shock" by understanding the breakdown between material and labor costs upfront.
- Transparent formulas based on current US industry standards for ready-mix and labor averages.
- Compare supply methods to see if DIY bagging is truly cheaper than a professional truck delivery.
- SEO and construction-ready precise calculations that help you negotiate better with local suppliers.
How to Estimate Your Slab Project
- Measure your slab Length, Width, and Thickness.
- Choose your Supply Method (Ready Mix is best for large areas, Bagged for tiny ones).
- Enter local Ready-Mix Prices (typically $150–$180 per yard) or Bag Prices.
- Input the Labor Rate if hiring a crew (usually $3–$10 per square foot depending on finish).
- Add Extras for gravel sub-base or rebar reinforcements.
- Click Calculate and save your PDF summary.
Calculation Formulas Behind the Tool
- Volume (ft³) = Length (ft) × Width (ft) × (Thickness (in) / 12)
- Volume (yd³) = Volume (ft³) / 27
Our tool handles all unit conversions internally so you can mix feet, inches, and meters.
- Material Cost = Adjusted Volume (yd³) × Price per Yard
- Adjusted Volume = Raw Volume × (1 + Waste %)
- Labor Cost = Total Area (sq ft) × Labor Rate ($/sq ft)
- Total Est. Cost = Materials + Labor + Extras (Reinforcement/Base)
Frequently Asked Questions
What is the average cost of a concrete slab per square foot?
In the US, most standard slabs cost between $6 and $12 per square foot installed. This includes both materials and professional labor. DIY projects using bagged mix may cost significantly less but require much more manual effort.
How much concrete do I need for a 20x20 slab?
A standard 4-inch thick 20x20 slab requires approximately 5 cubic yards of concrete. This includes a 10% waste allowance to cover spillage and sub-base variations.
Is it cheaper to use a concrete truck or buy bags?
Generally, projects requiring more than 1 cubic yard (about 45-50 bags) are cheaper and much faster via ready-mix truck. Bagged mix is ideal for small footings or tiny repairs where the truck delivery fee would outweigh the material cost.
What labor rate should I expect for my slab?
Labor rates vary by finish. A standard broom finish ranges from $3 to $5 per sq ft, while decorative stamped or polished finishes can exceed $10-$15 per sq ft.
Why do I need a waste allowance?
Soil is rarely perfectly flat. If your sub-grade is slightly lower in some areas, or if there is spillage during the pour, you will need more concrete than the exact mathematical calculation suggest. A 10-15% 'buffer' is industry standard.
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