Volume
20 × 20 × (4 ÷ 12)Net volume is 133.33 ft³Estimated. With 10% added, the total is 146.67 ft³Estimated.
2026 U.S. cost and quantity estimate
20x20 Concrete Slab Cost
In 2026, a 20x20 concrete slab costs $2,400–$4,800 installedVerified nationally and, at 4 inches thick with 10% added, needs about 5.43 cubic yardsEstimated or 245 80 lb bagsEstimated.
Installed cost source: HomeGuide, February 3, 2026. Quantity uses the dimensions and allowance shown.
20x20 concrete slab cost calculator
Adjust thickness, allowance, or metro area. All four planning results update in one step and remain in your browser.
Concrete volume
5.43 yd³
Includes selected allowance Estimated
80 lb concrete bags
245 bags
Whole bags, rounded up Estimated
Installed project cost
$2,400–$4,800
U.S. national benchmark Estimated
Installed price per sq ft
$6.00–$12.00
Thickness and metro adjusted Estimated
How to use this 20x20 calculator
01
Keep or change the footprint
The page starts at 20 ft by 20 ft. Changing either field recalculates area, volume, bags, and price.
02
Compare thickness
Switch among the supplied 4, 5, and 6 inch planning scenarios to see how volume changes.
03
Set the allowance
The default is 10%. This factor is applied after the rectangular slab volume is calculated.
04
Select the metro
The nearest listed metro changes only the modeled labor share. It does not claim a supplier quote.
20x20 slab calculation formula
The calculation moves from volume to cubic yards, then applies the relevant unit price.
Cubic yards and bags
146.67 ÷ 27 = 5.43 yd³Bag count divides the same volume by the verified 0.60 ft³ per 80 lb bagVerified, then rounds up.
Price
Quantity × unit price = costMaterial cost uses $120–$160/yd³Verified, HomeGuide, April 3, 2026. Installed cost starts with $6–$12/sq ftVerified.
Installed thickness model. HomeGuide reports that materials make up 50%–60%Verified and labor 40%–50%Verified of slab cost, February 3, 2026. This page uses midpoint shares of 55% material and 45% laborEstimated to model thickness and metro differences.
Concrete slab prices by size
These links keep the 2026 national installed benchmark visible across existing size pages.
| Size page | Area | 4-inch concrete | Installed cost | Data level |
|---|---|---|---|---|
| 10x10 concrete slab cost | 100 sq ft Estimated | 1.36 yd³ Estimated | $600–$1,200 Estimated | National installed baseline Estimated |
| 12x12 concrete slab cost | 144 sq ft Estimated | 1.96 yd³ Estimated | $860–$1,730 Estimated | HomeGuide $6–$12/sq ft, Feb. 3, 2026 |
| 20x20 concrete slab cost | 400 sq ft Estimated | 5.43 yd³ Estimated | $2,400–$4,800 Verified | HomeGuide, Feb. 3, 2026 |
| 20x30 concrete slab cost | 600 sq ft Estimated | 8.15 yd³ Estimated | $3,600–$7,200 Estimated | National installed baseline Estimated |
| 30x30 concrete slab cost | 900 sq ft Estimated | 12.22 yd³ Estimated | $5,400–$10,800 Estimated | National installed baseline Estimated |
| 30x40 concrete slab cost | 1,200 sq ft Estimated | 16.30 yd³ Estimated | $7,200–$14,400 Estimated | National installed baseline Estimated |
| 30x50 concrete slab cost | 1,500 sq ft Estimated | 20.37 yd³ Estimated | $9,000–$18,000 Estimated | HomeGuide $6–$12/sq ft, Feb. 3, 2026 |
| 40x60 concrete slab cost | 2,400 sq ft Estimated | 32.59 yd³ Estimated | $14,400–$28,800 Estimated | HomeGuide $6–$12/sq ft, Feb. 3, 2026 |
| 60x80 concrete slab cost | 4,800 sq ft Estimated | 65.19 yd³ Estimated | $28,800–$57,600 Estimated | HomeGuide $6–$12/sq ft, Feb. 3, 2026 |
20x20 slab thickness by use
The three thicknesses below are comparison scenarios supplied for estimating. They are not structural specifications or construction guidance.
Patio scenario
4 in Estimated5.43 yd³Estimated with the default allowance. Modeled installed range: $2,400–$4,800Verified baseline.
Driveway scenario
5 in Estimated6.79 yd³Estimated. Modeled installed range: $2,730–$5,460Estimated.
Load-bearing foundation scenario
6 in Estimated8.15 yd³Estimated. Modeled installed range: $3,060–$6,120Estimated.
Installed ranges in these scenarios use HomeGuide's $6–$12/sq ft national benchmarkVerified, dated February 3, 2026, with the disclosed thickness model applied where noted.
Concrete quantity and material cost by thickness
All rows cover 400 sq ft and include the default 10% allowance.
| Thickness | Cubic yards | 80 lb bags | Approx. weight | Ready-mix material cost |
|---|---|---|---|---|
| 4 in | 5.43 yd³ Estimated | 245 Estimated | 20,530 lb / 10.27 tons Estimated | $650–$870 Estimated |
| 5 in | 6.79 yd³ Estimated | 306 Estimated | 25,670 lb / 12.83 tons Estimated | $810–$1,090 Estimated |
| 6 in | 8.15 yd³ Estimated | 367 Estimated | 30,800 lb / 15.40 tons Estimated | $980–$1,300 Estimated |
Installed prices in this table use a single national $6–$12/sq ft baseline and do not change by thickness. See how price shifts by slab depth →
Material estimate: cubic yards × $120–$160/yd³ ready-mixVerified, HomeGuide, April 3, 2026. Weight uses 140 lb/ft³Verified, QUIKRETE technical data revised October 2022. Bag yield is 0.60 ft³Verified per 80 lb bag from the same sheet.
20x20 slab cost by metro area
Metro estimates adjust the labor share with BLS May 2025 construction and extraction wages. They do not represent ZIP-code or supplier quotes.
| Metro area | BLS construction wage | Modeled $/sq ft | 20x20 installed total | Level |
|---|---|---|---|---|
| Dallas concrete cost | $27.03/hr Verified | $5.62–$11.25 Estimated | $2,250–$4,500 Estimated | BLS May 2025 model |
| Chicago concrete cost | $40.87/hr Verified | $6.81–$13.62 Estimated | $2,720–$5,450 Estimated | BLS May 2025 model |
| Seattle concrete cost | $42.11/hr Verified | $6.92–$13.84 Estimated | $2,770–$5,530 Estimated | BLS May 2025 model |
| Atlanta concrete cost | $28.26/hr Verified | $5.73–$11.46 Estimated | $2,290–$4,580 Estimated | BLS May 2025 model |
Sources: BLS OEWS metro data, May 2025, and HomeGuide's $6–$12/sq ftVerified national range, February 3, 2026.
DIY material baseline vs. installed price
This is a cost-scope comparison only. The two cards do not contain the same line items.
DIY: ready-mix material only
$650–$870 EstimatedCalculated as 5.43 yd³Estimated multiplied by HomeGuide's $120–$160/yd³Verified, April 3, 2026. Other materials, equipment, delivery modifiers, and labor are outside this card.
Contractor: installed benchmark
$2,400–$4,800 VerifiedCalculated from the 400 sq ft footprint and HomeGuide's verified $6–$12/sq ft installed national range dated February 3, 2026.
Modeled difference: $1,530–$4,150Estimated. This is the gap between a ready-mix-only amount and the installed benchmark, not a complete DIY budget.
Items that can change a 20x20 quote
These published unit ranges help identify which line item is moving a bid. They are not automatically included in every total.
Base preparation
$1–$3/sq ft VerifiedGravel pad-base pricing reported by HomeGuide, February 3, 2026. Across 400 sq ft, that is $400–$1,200Estimated.
Rebar or wire-mesh upgrade
+$1–$4/sq ft VerifiedReinforcement-upgrade impact from HomeGuide's contractor pricing guide, April 3, 2026. For this footprint: +$400–$1,600Estimated.
Expansion-joint material
$0.50–$2/LF VerifiedMaterial-only range from HomeGuide's contractor pricing guide, April 3, 2026. Installed joint labor may appear separately.
Stamped or decorative finish
+$3–$12/sq ft VerifiedPublished add-on from HomeGuide, April 3, 2026. Across 400 sq ft: +$1,200–$4,800Estimated.
20x20 concrete slab cost FAQ
How many cubic yards are needed for a 20x20 concrete slab?
A 20x20 slab at 4 inches thick needs about 5.43 cubic yards with 10% addedEstimated. The same footprint needs 6.79 yd³ at 5 inchesEstimated and 8.15 yd³ at 6 inchesEstimated.
How much does a 20x20 concrete slab cost in 2026?
The verified national installed range is $2,400–$4,800 in 2026Verified. That is 400 sq ft multiplied by HomeGuide's $6–$12/sq ftVerified benchmark dated February 3, 2026.
What is the cost difference between 4 inches and 6 inches?
The modeled installed difference is $660–$1,320Estimated. The 4-inch benchmark is $2,400–$4,800Verified, while the 6-inch model is $3,060–$6,120Estimated. The latter uses the disclosed 55% material / 45% labor model.
How much could DIY save?
The narrow ready-mix-only comparison shows a $1,530–$4,150 gapEstimated. It compares $650–$870Estimated in ready-mix with the verified installed range; it does not count other DIY cost categories.
Can a 20x20 slab fit two cars or work as a patio?
A 20x20 footprint contains 400 square feetEstimated and is commonly categorized as a two-car garage or driveway size. HomeGuide lists two-car garage floors at 20x20 to 24x24 ftVerified, February 3, 2026. The same 400 sq ftEstimated footprint also represents a large patio area; actual usable layout depends on the objects and access occupying it.
How do I tell whether a 20x20 quote is reasonable?
Divide the quoted total by 400 sq ft and compare that unit rate with the metro-adjusted calculator range. Then compare separately listed base, reinforcement, joint, and finish charges with the sourced units on this page. The result is a price check, not a determination of required scope.
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