6-Inch Concrete Slab Cost 2026: $8 to $18 Per Square Foot
Six inches with a rebar grid is what contractors usually pour for slabs that carry vehicles: driveways, garage floors and parking pads. A standard 24x24 two-car garage floor at that spec costs about $6,510 installed, $4,420 to $10,560 from the lowest published prices to the highest, or $8 to $18 per sq ft. That is about $1,950 more than the same floor at 4 inches with mesh.
Trade Practice, Not a Model-Code Rule
The model International Residential Code sets one slab-on-ground thickness, R506.1’s 3½-inch minimum, and adds nothing for vehicles. Driveways are outside its scope. Six inches with a #4 rebar grid is the specification contractors commonly use for slabs that carry cars and trucks, because the loads are concentrated at the tires and repeated every day, and some cities write their own driveway-approach standards. If yours has one, it governs.
Concrete strength is where the code does single out garages. IRC Table R402.2 puts garage floor slabs in the same row as porches, carport slabs and steps exposed to the weather: 2,500 PSI where the weathering potential is negligible, 3,000 PSI moderate, 3,500 PSI severe. Its footnote allows the air content of a steel-troweled garage floor to drop to 3 percent if the strength is raised to at least 4,000 PSI, which is one reason garage floors are so often poured at 4,000 PSI. Our 6-inch prices use 4,000 PSI ready-mix at $132.00 to $175.00 a yard from four published price lists.
For recreational vehicles and heavy equipment, see the 8-inch slab page. Five inches is a middle option some contractors offer for driveways: a 24x24 at 5 inches with the same rebar grid comes to about $5,920 in our model.
Rebar Size, Spacing and Placement
Our 6-inch prices assume #4 bar (1/2 inch, Grade 60, sold in 20 ft lengths) on an 18-inch grid each way. For a 24x24 floor that is about 845 ft of bar once laps are allowed for, or 43 bars at $8.99 each at Menards, plus plastic chairs at $0.33 each: about $427 of steel in all, or $0.74 per sq ft. Mesh would be about $0.24 per sq ft. Tighter spacing means more bar and more tying time; ask the contractor to state the bar size and spacing on the quote.
Placement is the one place where the IRC is prescriptive about steel. R506.2.4 requires that reinforcement, where provided, be “supported to remain in place from the center to upper one-third of the slab for the duration of the concrete placement.” On a 6-inch slab that means chairs that hold the grid at least 3 inches up, not bar laid on the stone and pulled up during the pour. Check the chairs before the concrete arrives. See rebar vs wire mesh for the comparison.
Cold Climates and Air-Entrained Concrete
The footnotes to IRC Table R402.2 require concrete in moderate and severe weathering areas to be air-entrained, with total air content “not less than 5 percent or more than 7 percent”, for the rows the table marks. That is the code’s freeze-thaw protection: tiny air voids that give freezing water room to expand. The garage-floor footnote above is the exception for a steel-troweled finish.
Ask your ready-mix supplier or contractor which exposure class your area falls in and what air content they will order. None of the four price lists we use publishes a separate charge for air entrainment.
6-Inch Slab Cost for Common Sizes
| Sq Ft | Concrete (cu yd) | Low | Typical | High | Typical Use |
|---|---|---|---|---|---|
| 200 (10x20) | 3.7 | $1,800 | $2,770 | $4,670 | Single parking pad |
| 240 (12x20) | 4.44 | $2,020 | $3,070 | $5,250 | 1-car garage |
| 400 (20x20) | 7.41 | $3,170 | $4,690 | $7,430 | Compact 2-car garage, driveway |
| 576 (24x24) | 10.67 | $4,420 | $6,510 | $10,560 | Standard 2-car garage |
| 720 (24x30) | 13.33 | $5,450 | $7,960 | $12,640 | Large 2-car or small 3-car |
| 1,000 (25x40) | 18.52 | $7,440 | $10,780 | $17,280 | Workshop with vehicles |
Every row: 6-inch, 4,000 PSI, #4 rebar at 18 inches, 4-inch crushed-stone base, broom finish, national prices. Low uses the lowest published price and our lowest labour assumption at every step; high uses the highest. Coatings, decorative finishes, drains and removal of an old slab are not included. The garage slab page prices 1, 2 and 3-car floors at this spec.
How the 6-Inch Spec Differs by Use
A driveway and a garage floor can share the same thickness and steel and still differ in the details. A driveway is outdoors, so in a freeze-thaw area its concrete should be air-entrained as Table R402.2 sets out, and it is outside the IRC, so local driveway rules apply. A garage floor is inside a building that normally needs a permit (IRC R105.1), and the 4,000 PSI footnote applies if it gets a steel-troweled finish.
Neither needs a vapor retarder under the model code (R506.2.3 exempts garages, unheated accessory structures and driveways), but a garage that will be heated or converted later is worth fitting with one: about $41 of 6-mil poly for a 24x24. The garage slab cost page and driveway cost page have application-specific detail.
How We Price a Slab
Every installed price on this site comes from one model: published ready-mix and materials prices, plus crew hours priced at Bureau of Labor Statistics wages, plus overhead and margin. The low figure uses the lowest published input and our lowest assumption at every step; the high figure uses the highest. The crew hours, overage and margin are our own estimates, not published figures, and are listed below so you can check them against your quote. Worked example: a 24 x 24 ft two-car garage floor (6-inch, 4,000 PSI, #4 rebar at 18 in, broom finish, 4-inch stone base).
| Line | Low | Typical | High | Basis |
|---|---|---|---|---|
| Ready-mix concrete | $1,478 | $1,709 | $2,053 | 10.67 cu yd plus 5 to 10% overage, at published per-yard prices |
| Delivery and small-load charges | $0 | $70 | $838 | Per-truck charges from the same price lists (10 yd per truck) |
| Crushed-stone base | $375 | $468 | $638 | 4 in compacted crusher run |
| Reinforcement | $427 | $427 | $427 | #4 bar at 18 in each way, laps and chairs |
| Form lumber | $57 | $86 | $115 | Perimeter boards, shared across reuses |
| Crew labour | $1,345 | $2,247 | $3,474 | Crew hours x BLS wages x employer costs |
| Overhead and margin | $737 | $1,502 | $3,018 | 20% to 40% on direct cost |
| Installed total | $4,420 | $6,510 | $10,560 | Rounded to the nearest $10 |
Not included: excavation and soil haul-off, removing an old slab, permits, pumping, decorative finishes and sealing. Totals are national; the calculators’ state option swaps in that state’s BLS wages and leaves concrete and materials at the published lists.
Published inputs (read 13 October 2026)
- Ready-mix, per cubic yard: 3,000 PSI $127.05 to $165.00, 4,000 PSI $132.00 to $175.00, from Supreme Concrete (Los Angeles, CA), Minimix Concrete (Pequannock, NJ), Gehring Construction & Ready-Mix (Columbus, NE, list dated 2026-01-01), Scenic City Ready Mix (Tennessee, list dated 2024-08-03).
- Small orders and trucks: short-load charge $50 under 4 yd (Gehring) or $100 at 5 yd or less, plus $100 more at 2 yd or less (Scenic City); per truck, no charge within 20 miles (Gehring), a $35 surcharge (Scenic City), or $363.88 Zone A delivery plus a $55 environmental fee (Supreme).
- Crushed-stone base: $44.00 to $74.75 per cubic yard from D & L Supply (Central New York, $44.00/yd), JMJ Companies (Lynchburg, VA, $39.50/ton), Golden Landscaping Supply (Cumming, GA, $50.00/ton), Yard Works Landscape Supply (Fort Mill, SC, $74.75/yd); per-ton prices converted at 2,450 lb per yard.
- Steel, forms, poly: #4 rebar 20 ft $8.99, 6x6 10-gauge mesh 4x8 panel $6.99, 2x6x12 $14.32, 2x4x16 $12.13, 6-mil poly 8 ft 4 in x 100 ft $59.99, rebar chair $0.33 (Menards online prices; Home Depot and Lowe’s pages could not be read that day). That works out to $0.24 per sq ft for mesh and $0.74 per sq ft for a rebar grid, materials only.
- Wages: BLS OEWS 47-2051 cement masons (May 2025) 25th percentile $22.60, median $27.41, 75th $32.15 an hour; 47-2061 construction laborers $18.57, $22.66, $28.72. Employer costs from BLS ECEC June 2026, construction industry ($51.96 total compensation per $36.13 of wages, x1.44): a crew hour costs $29.60 to $43.77.
Our assumptions (estimates, not published figures)
- Crew: half cement masons, half laborers.
- Setup per job: 8 to 16 crew hours (layout, stripping, cleanup).
- Per 100 sq ft: 4-inch 4 to 7 crew hours, 6-inch 5 to 8.5, 8-inch 6 to 10; add 0.5 to 1 for mesh or 1.5 to 2.5 for rebar.
- Concrete overage 5% to 10%; base stone ordered at 1.2x its compacted volume; form boards charged at half to all of their price.
- Overhead and margin 20% to 40% of direct cost.
- 6-inch and thicker slabs use 4,000 PSI mix; thinner slabs 3,000 PSI.
Sources: BLS OEWS 47-2051 cement masons (May 2025), BLS OEWS 47-2061 construction laborers (May 2025), BLS ECEC, construction (June 2026), ready-mix price lists from Supreme Concrete, Minimix Concrete, Gehring Construction & Ready-Mix, Scenic City Ready Mix, crusher-run prices from D & L Supply, JMJ Companies, Golden Landscaping Supply, Yard Works Landscape Supply, Menards mesh, rebar, lumber and poly prices, IRC R506.1, R506.2.3, R506.2.4, Table R402.2 (2018 IRC as adopted in Minnesota, UpCodes) and R105.1. All read 13 October 2026. Crew hours, overage, overhead and margin are our estimates and are listed in the method above.