Concrete Slab Cost Calculator

What a concrete slab costs

A concrete slab cost calculator prices a slab in two parts: the concrete, which depends on volume, and the labor, which depends on area. Cost = (L × W × depth in ÷ 12 ÷ 27) × price per yd³ + (L × W) × labor per sq ft. At $150 per cubic yard and $6 per square foot of labor, a 10 × 10 ft slab 4 inches thick costs $185.19 in concrete and $600 in labor, for $785.19.

The result panel shows the cubic yards and the combined cost. Both prices are editable, so replace them with your supplier’s and contractor’s figures.

Why the two costs grow differently

Labor is the bigger share on most small slabs. A finisher spends roughly the same effort screeding and troweling a 4-inch slab as a 6-inch one, so labor follows the area. Concrete follows the volume, so a thicker slab raises only the material line.

At the defaults, each extra inch of thickness adds about $0.46 per sq ft. Doubling the area doubles both lines.

Worked examples

Example 1: Patio slab at default rates, 10 × 10 ft, 4 in

• Volume: 10 × 10 × 0.333 ÷ 27 = 1.23 yd³
• Concrete: 1.235 × $150 = $185.19
• Labor: 100 sq ft × $6 = $600.00
• Total: $785.19

Example 2: Two-car garage floor, 24 × 24 ft, 6 in, $160 per yd³, $7 per sq ft labor

• Volume: 24 × 24 × 0.5 ÷ 27 = 10.67 yd³
• Concrete: 10.667 × $160 = $1,706.67
• Labor: 576 sq ft × $7 = $4,032.00
• Total: $5,738.67

Example 2 does not include rebar, a vapor barrier, or the stone base. A garage slab normally needs all three.

Cost at the default rates

Slab size	Thickness	Cubic yards	Concrete	Labor	Total
10 × 10 ft	4 in	1.23	$185.19	$600	$785.19
12 × 12 ft	4 in	1.78	$266.67	$864	$1,130.67
10 × 20 ft	4 in	2.47	$370.37	$1,200	$1,570.37
16 × 20 ft	4 in	3.95	$592.59	$1,920	$2,512.59
24 × 24 ft	4 in	7.11	$1,066.67	$3,456	$4,522.67
24 × 24 ft	6 in	10.67	$1,600.00	$3,456	$5,056.00

Line items to add to the estimate

Item	How it is usually priced
Excavation and grading	Per sq ft or per job
Compacted gravel base	Per ton or yard of stone
Forms and edge boards	Per linear foot of perimeter
Rebar or wire mesh	Per sq ft or per bar
Vapor barrier (interior slabs)	Per roll
Pump truck	Per hour or per job
Short-load fee	Flat fee below the supplier’s minimum
Permit	Set by your building department

How to measure for a quote

1. Measure the finished slab inside the forms, in feet.
2. Split L-shapes into rectangles and run each one, then add the totals.
3. Use the design thickness. Patios are often 4 inches and driveways 5 to 6 inches. Garage and structural slabs follow local code.
4. Check for thickened edges. Perimeter footings add volume, not area. Price them separately with the concrete slab calculator.

Common mistakes

• Comparing a quote to material cost only. Labor and prep often make up most of the price.
• Leaving the placeholder rates in. National defaults rarely match your area.
• Forgetting minimum charges. Small jobs often carry a mobilization fee that makes the per-foot price look high.
• Skipping reinforcement in the budget. Size the steel with the rebar calculator.

Related calculators

For specific jobs, try the concrete patio cost calculator or the concrete driveway cost calculator. Structural slabs should be designed or reviewed by a licensed engineer or contractor.