20x20 Concrete Slab Cost: $2,180 to $5,620 (2026)
A 20x20 concrete slab costs about $3,360 installed at 4 inches thick with wire mesh, on a 4-inch crushed-stone base with a broom finish: $2,180 to $5,620 from the lowest published prices to the highest ($5.45 to $14.06 per sq ft). Built as a garage floor (6 inches, 4,000 PSI, rebar) it is about $4,690. These are our October 2026 model figures, built from published ready-mix, stone and materials prices and BLS wages; the method is at the foot of the page.
20x20 Concrete Slab Cost by Thickness
Thickness sets the concrete volume, and the steel that goes with it sets most of the rest. The same model prices each row: published ready-mix and stone prices, Menards steel and lumber, crew hours at Bureau of Labor Statistics wages, and a stated overhead and margin.
| 20x20 slab | Concrete | Installed cost |
|---|---|---|
| 4-inch, no reinforcement 3,000 PSI, broom finish | 4.94 yd 223 bags | $3,100 $1,990 to $5,240 $7.75 per sq ft |
| 4-inch, wire mesh 3,000 PSI, 6x6 mesh | 4.94 yd 223 bags | $3,360 $2,180 to $5,620 $8.41 per sq ft |
| 5-inch, rebar 4,000 PSI, #4 bar at 18 in | 6.17 yd 278 bags | $4,300 $2,870 to $6,920 $10.76 per sq ft |
| 6-inch, rebar 4,000 PSI, #4 bar at 18 in | 7.41 yd 334 bags | $4,690 $3,170 to $7,430 $11.72 per sq ft |
| 8-inch, rebar 4,000 PSI, #4 bar, 6-inch base | 9.88 yd 445 bags | $5,690 $3,880 to $9,360 $14.23 per sq ft |
Installed cost is the typical figure, then low to high. All rows: broom finish, compacted crushed-stone base (4 inches, or 6 under the 8-inch slab), national prices, no excavation. Bags are 80 lb at QUIKRETE’s stated 0.60 cubic feet each, before overage. Low uses the lowest published price and our lowest labour assumption at every step; high uses the highest.
More on each: 4-inch slab cost, 6-inch slab cost and 8-inch slab cost.
Which 20x20 Slab Do You Need?
The footprint is the same; what it has to carry decides the spec, and the spec decides the price. A quote for a 20x20 slab should name its thickness, PSI and reinforcement. If yours does not, ask, because two quotes for different specs cannot be compared.
| Use | Usual spec | Typical |
|---|---|---|
| Patio, hot tub base, walkway Carries people and furniture, not vehicles. IRC R506.1 sets 3.5 inches as the minimum for a floor slab. Patio cost | 4-inch, wire mesh | $3,360 |
| Shed or workshop floor Same spec as a patio. An unheated accessory building is exempt from the IRC R506.2.3 vapor retarder. Shed slab cost | 4-inch, wire mesh | $3,360 |
| Parking pad or basketball half court The 4,000 PSI mix our driveway and basketball court pages price for slabs that cars drive on. Basketball court cost | 4-inch, 4,000 PSI, mesh | $3,410 |
| Compact two-car garage floor The usual spec for a slab that carries cars every day. A garage floor is part of the building, which needs a permit (IRC R105.1). Garage slab cost | 6-inch, 4,000 PSI, rebar | $4,690 |
| RV, trailer or equipment pad Heavy, concentrated wheel loads. Have the thickness set by whoever specifies the load, not by this table. RV pad cost | 8-inch, 4,000 PSI, rebar | $5,690 |
The International Residential Code does not require reinforcement in a slab on the ground (R506.2.4 only says how steel must be supported where it is used), so mesh and rebar are design choices. Local codes, your engineer or a garage kit’s drawings can require more. 20x20 is sold as a compact two-car size, but there is no standard; our garage page prices 24x24.
Price Your 20x20 Slab
Enter 20 and 20 (or your exact size), then open the options to change the thickness, reinforcement and state. The calculator runs the same model as the tables, with your state’s BLS wages for the crew.
Concrete Slab Cost Calculator
Replacing an Old Slab, Digging Out, Bags vs a Truck
Removing an old 20x20 slab. Eight contractors bid $1.00 to $3.05 a sq ft to remove concrete in the Village of River Forest, Illinois bid tabulation (December 2025): $400 to $1,220 for 400 sq ft, on top of the new slab. Those are unit prices on a large municipal program, so one small job can cost more. The removal and replacement page prices the two together.
Digging out. The prices above assume the ground only needs its stone base. Cutting a level pad out of soil, and hauling that soil away, is quoted separately; the site prep page models it from published rental rates and landfill fees.
Bags or ready-mix. A 4-inch 20x20 slab is 223 bags of 80 lb mix. At $9.99 a bag (one Ace Hardware store, 13 October 2026) that is about $2,228 in bags, each one mixed and placed by hand. The 5.19 to 5.43 yards a truck would bring clears the small-load fees on the published price lists we use, which apply at 4 or 5 yards and under. See the DIY slab guide before taking it on yourself.
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 20 x 20 ft slab, 4-inch with wire mesh (4-inch, 3,000 PSI, wire mesh, broom finish, 4-inch stone base).
| Line | Low | Typical | High | Basis |
|---|---|---|---|---|
| Ready-mix concrete | $659 | $754 | $896 | 4.94 cu yd plus 5 to 10% overage, at published per-yard prices |
| Delivery and small-load charges | $0 | $35 | $419 | Per-truck charges from the same price lists (10 yd per truck) |
| Crushed-stone base | $261 | $325 | $443 | 4 in compacted crusher run |
| Reinforcement | $96 | $96 | $96 | 6x6 10-gauge mesh panels, lapped |
| Form lumber | $30 | $45 | $61 | Perimeter boards, shared across reuses |
| Crew labour | $770 | $1,332 | $2,101 | Crew hours x BLS wages x employer costs |
| Overhead and margin | $363 | $776 | $1,606 | 20% to 40% on direct cost |
| Installed total | $2,180 | $3,360 | $5,620 | 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 and lumber prices, QUIKRETE Concrete Mix data sheet (bag yield), Village of River Forest 2026 curb and sidewalk bid tabulation, IRC R105.1, R506.1, R506.2.3 and R506.2.4. Model inputs read 13 to 14 October 2026; Gehring and Minimix ready-mix prices re-read 30 October 2026, unchanged. Crew hours, overage, overhead and margin are our estimates and are listed in the method above.