Concrete Slab Cost Calculator

Enter your slab dimensions to get instant cubic yards, bag count, and total project cost — including materials and typical labor rates.

How to Calculate Concrete Slab Cost

The formula is simple: Volume = Length × Width × Thickness. Convert everything to feet, then divide by 27 to get cubic yards. One cubic yard of concrete covers an 81 sq ft area at 4 inches thick.

Most projects add a 10% waste factor to account for spillage, uneven subgrade, and over-excavation. Our calculator applies this automatically based on your selection.

What Affects the Final Price?

Concrete Type

Standard 3,000 PSI concrete costs $140–$170 per cubic yard in most US markets. Higher PSI (4,000–5,000) for structural work runs $170–$220. Fiber mesh or rebar reinforcement adds $0.30–$1.00 per square foot.

Labor

Finishing labor runs $3–$8 per square foot, depending on complexity. Decorative finishes (stamped, exposed aggregate) can push this to $15–$25 per square foot.

Site Access

If a concrete truck can't reach your pour site, you'll pay pump truck fees ($500–$1,500) or need to wheelbarrow the concrete (adding significant labor).

Frequently Asked Questions

How many bags of concrete do I need for a 10x10 slab?

A 10×10 slab at 4 inches thick requires 1.23 cubic yards, or about 56 bags of 80-lb concrete mix. For larger pours, ready-mix delivery is far cheaper per yard.

How much does a 20x20 concrete slab cost?

At 4 inches thick, a 20×20 slab (400 sq ft) needs about 4.94 cubic yards. At $150/yard that's $740 in materials, plus $2,400 in labor for a total of roughly $3,100–$3,500.

Is it cheaper to mix my own concrete?

For slabs over 1 cubic yard, ready-mix is cheaper and far less labor. Bagged mix only makes sense for small repairs and footings under 20 bags.