Concrete Slab Cost Calculator: What You'll Actually Pay in 2026

"How much does a concrete slab cost?" is the #1 question I get from people planning patios, garage floors, and shed bases. The frustrating answer: it depends. The useful answer: here's exactly what drives the price, with real numbers.

The quick answer

Most concrete slabs cost $4–$8 per square foot installed (4" thick, standard finish). A 10×10 ft patio slab runs roughly $400–$800 for materials if you DIY, or $600–$1,200 hired out.

| Slab thickness | DIY materials (per sq ft) | Contractor installed (per sq ft) | |---|---|---| | 3" (light use) | $2–$3 | $4–$6 | | 4" (standard) | $2.50–$3.50 | $5–$8 | | 6" (heavy duty) | $4–$5 | $7–$12 |

What drives the cost

1. Thickness matters more than you think. Going from 4" to 6" isn't 50% more concrete — it's literally 50% more material, plus heavier labor. Don't overspec: a garden shed doesn't need a 6" slab.

2. Site prep is the hidden cost. If your ground is already flat and compacted, great. If the contractor has to excavate 6 inches, haul dirt, and bring in gravel base — that's often $1–$2/sq ft before a single bag of concrete shows up.

3. Finish adds up. Broom finish (standard, included). Stamped/patterned concrete? Add $3–$5/sq ft. Exposed aggregate? Another $2–$3/sq ft. That "cheap patio" gets expensive fast with decorative finishes.

4. Rebar vs. wire mesh. Wire mesh: ~$0.30/sq ft. Rebar grid: ~$0.75/sq ft. For a 4" residential slab, mesh is usually fine. For driveways and heavy loads, rebar is worth it.

DIY vs contractor: honest math

10×10 ft patio, 4" thick:

DIY:

• Concrete: ~1.25 yards (56 bags) or short-load delivery: $200–$300
• Gravel base: $50–$80
• Lumber for forms + mesh: $60–$100
• Mixer rental: $50
• Total: ~$360–$530 + your weekend

Contractor:

• All-in: $600–$1,000
• Done in a day, warranty included, no back pain

My take: under 100 sq ft, DIY is genuinely worth it. Over 200 sq ft, hire it out — the concrete truck alone changes the math, and a bad DIY pour is a permanent reminder of your mistakes.

5 mistakes that cost real money

1. Skipping the gravel base. Pouring on bare dirt = cracking within 2 years. $80 of gravel saves a $1,000 redo.
2. No control joints. Concrete WILL crack — joints control where. Cut every 8–10 ft.
3. Pouring in extreme heat. Above 90°F, concrete sets too fast and weakens. Pour early morning.
4. Under-ordering. Running short mid-pour creates a cold joint (weak seam). Order 10% extra.
5. No slope. A patio needs 1/4" per foot slope away from the house. Flat = puddles against your foundation.

Quick cost estimates (4" slab, DIY materials)

| Project | Size | Est. materials | |---|---|---| | Shed base | 8×10 ft | $200–$280 | | Patio | 12×12 ft | $360–$500 | | Garage floor | 20×20 ft | $1,000–$1,400 | | Driveway section | 10×20 ft | $500–$700 |

Want the exact numbers for your project? Our free concrete calculator gives you cubic yards, bag counts, and material estimates instantly.