Concrete Slab Cost Calculator

A basic concrete slab costs $4–$8 per square foot for a 4-inch slab with no special finish. A 6-inch slab runs $6–$10/sq ft. With reinforcement (wire mesh or rebar), add $0.50–$1.50/sq ft. Decorative finishes like stamped or colored concrete add $2–$6/sq ft. A typical 600 sq ft driveway slab costs $3,600–$7,200 installed, or $5,000–$12,000 with reinforcement and finishing.

4 inches is standard for patios, walkways, and garage floors. 5 inches is recommended for residential driveways. 6 inches is required for heavy vehicle traffic, RV pads, and commercial driveways. 8+ inches is used for shop floors supporting heavy equipment. Thicker slabs cost more but resist cracking under heavy loads. The subgrade must also be properly compacted — a thick slab on poor soil still fails.

Wire mesh ($0.15–$0.40/sq ft) is the most common — 6×6 W1.4/W1.4 welded wire mesh prevents small cracks from spreading. Rebar grid ($0.75–$1.50/sq ft) uses #3 or #4 rebar on 12–18-inch centers for structural strength. Fiber mesh ($0.10–$0.25/sq ft) is mixed into the concrete to resist hairline cracking. Post-tension cables ($2–$4/sq ft) are used on expansive soils. Most residential slabs use wire mesh or rebar.

Broom finish (standard, no extra cost) provides slip resistance for driveways and sidewalks. Smooth/trowel finish ($0–$1/sq ft extra) for garage floors and indoor slabs. Exposed aggregate ($2–$4/sq ft extra) reveals decorative stones in the surface. Stamped concrete ($3–$6/sq ft extra) mimics brick, slate, or flagstone patterns. Colored/stained concrete ($2–$4/sq ft extra) adds integral or surface-applied color.

Most municipalities require a building permit for concrete slabs over a certain size (typically over 200 sq ft) or for any attached structure like a garage floor or driveway. Permit costs range from $50–$500 depending on your location and project scope. Some areas also require an engineering review or soil test for slabs on expansive soils. Always check with your local building department before pouring.

Small slabs under 100 sq ft (a small pad or walkway section) are reasonable DIY projects using bagged concrete. Larger slabs require ordering ready-mix concrete, and you must have enough help to place, screed, and finish the concrete before it sets (typically within 1–2 hours). DIY saves $2–$5/sq ft on labor but requires forms, tools (screed board, bull float, edger, trowel), and physical endurance. Mistakes in large pours are expensive to fix.

Spring and fall are ideal — temperatures between 50°F and 80°F allow proper curing. Summer pours work but require extra precautions: shade the area, use cool water, and consider evaporation retarders. Avoid pouring when temperatures will drop below 40°F within 48 hours, as freezing concrete loses strength permanently. Concrete poured in extreme heat (above 90°F) may crack from rapid moisture loss.

Concrete reaches initial set in 24–48 hours (safe for foot traffic). Working strength (safe for building on or parking) is reached in 5–7 days. Full design strength (4,000 PSI for standard mix) is reached at 28 days. Keep the slab moist for the first 7 days by covering with plastic sheeting or applying curing compound. Do not seal or coat the slab until it has cured for at least 28 days.