Typical Installed Range
Most 20x20 slabs fall between $2,400 and $7,200 installed, from a simple 4-inch broom finish to decorative or structurally reinforced work.
Guides
What is the typical cost for a 20x20 concrete slab in the Phoenix area?
Phoenix Concrete Co. explains that a 20x20 concrete slab typically costs $2,400 to $7,200, with thickness, finish, reinforcement, grading, and access shaping the final quote. The footprint is 400 square feet, but concrete volume rises from about 4.94 cubic yards at 4 inches thick to about 7.41 cubic yards at 6 inches.
Quick Summary
- A complete 20x20 slab typically costs $2,400 to $7,200, depending on thickness, reinforcement, finish, and site conditions.
- A basic 4-inch broom-finish slab usually runs $2,400 to $4,800, while a decorative 20x20 patio runs $3,200 to $7,200.
- Phoenix-area base pricing often runs $4.10 to $8.30 per square foot, and ready-mix costs $114 to $165 per cubic yard depending on strength and additives.
- Excavation or grading can add several hundred dollars, while spring and fall generally offer more manageable Phoenix curing conditions.
20x20 Slab Cost at a Glance
Thickness Drives Yardage
Moving from 4 inches to 6 inches raises concrete volume from about 4.94 to 7.41 cubic yards, an increase of roughly 50%.
Quote the Entire Scope
Compare excavation, base preparation, forming, reinforcement, concrete strength, finish, access, and curing measures-not just the concrete price.
What Changes a 20x20 Slab Quote
400-Square-Foot 4-Inch Broom-Finish Slab
This is the most useful baseline for a simple residential quote: a level 20x20 footprint, 4-inch thickness, and a broom finish.
4-Inch Patio and 6-Inch Garage Slab Cross-Sections
A side-by-side cross-section makes the roughly 50% increase in concrete volume and the heavier garage reinforcement easy to see.
Phoenix Slab Forms, Grade, and Pour Access
Visible forms, base preparation, drainage slope, and concrete-delivery access show why site conditions can change the installed price.
20x20 Slab Pricing Snapshot
Standard Installed Range
Standard residential installation generally runs $2,400 to $6,500; decorative work can take the overall range to $7,200 or higher.
Local Per-Square-Foot Range
Simple Phoenix and Maricopa County work often runs $4.10 to $8.30 per square foot, compared with a $6 to $12 national installed range.
Application Cost Ranges
Typical source ranges are $3,200 to $7,200 for a patio, $3,500 to $6,500 for a garage slab, and $4,000 to $7,500 for a driveway slab.
Cost Share by Scope
About 40% of a quote may go to materials and 45% to labor and finishing, with the remainder covering site preparation, permits, and reinforcement.
20x20 Slab Cost Comparison Chart
| 20x20 Slab Type | Typical Source Range | Main Cost Drivers |
|---|---|---|
| 4-inch broom finish | $2,400 to $4,800 | About 4.94 cubic yards, forming, placing, and finishing |
| Shed slab | $2,400 to $3,800 | 4-inch thickness and wire mesh reinforcement |
| Decorative patio | $3,200 to $7,200 | Color, texture, grading, and drainage slope |
| 6-inch garage slab | $3,500 to $6,500 | About 7.41 cubic yards, rebar, strength, and vapor barrier |
| Driveway slab | $4,000 to $7,500 | Higher-strength mix, reinforcement, and grading |
| Stamped or colored patio | $6,000 to $9,000 | Pattern, color, and finish labor |
What a 20x20 Slab Estimate Means
A 20x20 slab is exactly 400 square feet, but ready-mix is purchased by the cubic yard. A 4-inch slab takes about 4.94 cubic yards, while a 6-inch slab takes about 7.41 cubic yards; contractors often allow 5% to 10% overage for grade variation and spillage. That is why identical footprints can produce different material bills.
Factors That Change the Final Cost
For a 4-inch slab, material alone runs $925 to $1,100 using $125 to $150 per-cubic-yard pricing; broader Phoenix ready-mix pricing runs $114 to $165 per cubic yard depending on strength class and additives. Materials may account for $3 to $7 per square foot and labor for another $3 to $5 per square foot. Moving from 4 to 6 inches can add $700 to $1,500, while tight access, excavation, grading, decorative finishes, fiber mesh, rebar, or hot-weather curing measures can add further cost.
Common Follow-Up Questions
DIY materials and rental equipment may total $1,500 to $2,500, but professional work includes base compaction, control-joint layout, slump judgment, and finish execution. The 4-2-1 rule means 4 parts gravel, 2 parts sand, and 1 part cement for basic hand mixing; structural slabs instead use specified ready-mix strength. Poured concrete is generally less expensive per square foot than pavers, while pavers allow individual-unit replacement; a properly reinforced and sealed concrete slab can provide 25 to 30 years of service in the desert climate when maintenance and sealing stay current. For scheduling, Phoenix-specific guidance favors late September through early May, while July through September adds monsoon risk and summer pours may require early starts, evaporation retarders, curing compound, or chilled mix water. The draft also identifies mid-April through mid-October as a broadly workable curing span before adjusting for Phoenix heat, so site-specific weather planning matters more than a generic calendar. For a larger comparison, a 20x40 slab covers 800 square feet, uses about 9.88 cubic yards at 4 inches, and generally costs $4,800 to $12,000.
Plan a Site-Specific Quote
Need a 20x20 Slab Estimate?
Share the intended use, preferred finish, slab thickness, property grade, and delivery access. A written estimate should separate concrete, reinforcement, site preparation, forming, finishing, and any hot-weather measures so you can compare the same scope across quotes.