20x30 Concrete Slab Cost
A rebar-reinforced 20x30 concrete slab costs $4,983 to $8,306 installed at 4 inches, or $8.31 – $13.84 per square foot. Put your ZIP in the calculator to use local wages instead of national ones.
LIKELY INSTALLED PRICE
$6,645
Our installed range for this 20×30 ft, 4-inch slab: $4,983 – $8,306 ($8.31 – $13.84 per sq ft)
In plain terms: that's about the size of a two-car garage pad, and roughly 45% of the price is the crew's labor.
- DIY materials
- $3,490
- Concrete
- 7.41 yd³
- Bagged mix
- 367 80-lb bags
- Delivery
- 1 truck
An estimate, not a bid. A contractor's price depends on your site, access and timing.
What changes the price
Where the money goes
- Materials$3,023
- Labor$2,514
- Overhead and profit (20%)$1,107
All 8 line items
| Item | Qty | Material | Labor | Total |
|---|---|---|---|---|
| Site setup, layout and cleanup | 1 job | $100 | $56 | $156 |
| Excavate and grade subgrade | 600 sqft | $0 | $666 | $666 |
| Forms, stakes and form release | 100 lf | $120 | $222 | $342 |
| Compacted crushed-stone base | 10.37 ton | $467 | $192 | $659 |
| #4 rebar, tied on chairs | 850 lf | $848 | $377 | $1,225 |
| Ready-mix concrete, 3,500 psi, delivered | 7.78 yd3 | $1,353 | $173 | $1,526 |
| Place, screed and broom finish | 600 sqft | $30 | $777 | $807 |
| Sawn control joints | 70 lf | $105 | $52 | $157 |
| Subtotal × overhead and profit (20%) = midpoint | $6,645 | |||
National prices until you enter a ZIP.
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Compare a contractor's price with the range for these inputs.
What next
Get two or three quotes and compare them with $4,983 – $8,306. DIY: 367 bags or 7.78 yd³ of ready-mix.
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Turn this price into an estimate for your customer →Cost by thickness for 20x30 (600 sq ft)
4 in · patios, sheds
$4,983 – $8,306
7.41 yd³ · 367 bags · about $6,645
5 in · garages, driveways
$5,327 – $8,878
9.26 yd³ · 459 bags · about $7,102
6 in · shops, RV pads
$5,630 – $9,383
11.11 yd³ · 550 bags · about $7,506
- Typical use
- A two-car garage with room for a workbench along one wall.
- Thickness
- 4 inches with rebar for cars; go thicker where a lift or heavy equipment will stand.
- Planning note
- If a car lift is planned, tell the contractor now, because lifts need a thicker pad under the posts.
What a 20x30 slab gets used for
A 600-square-foot slab suits a two-car garage with a workbench wall, a large carport or a small shop. The extra depth over a 20x20 is usually for storage or a bench.
20x30 slab cost with rebar
This size is priced with 850 linear ft of rebar rather than mesh, which helps a larger slab under vehicles. The line items show the steel, gravel and labor separately.
Planning the pour
The order is 7.78 yd³ with waste, on 1 truck. The forms run 100 linear ft, and a long reach from the street may add a pump.
Estimate, not a bid
This number is for budgeting and for comparing quotes. A contractor's bid will account for your soil, grade and access, which this page can't see.
DIY vs pro for this 20x30 pour
Materials alone come to $3,490, about 53% of the $6,645 midpoint contractor price. The difference is $3,155 of labor, equipment, delivery and contractor overhead across 8 line items. At 7.78 yd³ with waste the pour fills 1 mixer truck, so ready-mix is the practical route even for a DIY pour.
Other popular slab sizes
- 12x20 concrete slab cost$1,922 – $3,203240 sq ft · 2.96 yd³ at 4 in
- 20x20 concrete slab cost$2,874 – $4,789400 sq ft · 4.94 yd³ at 4 in
- 24x24 concrete slab cost$4,848 – $8,080576 sq ft · 7.11 yd³ at 4 in
- 20x40 concrete slab cost$6,562 – $10,936800 sq ft · 9.88 yd³ at 4 in
- 30x30 concrete slab cost$7,324 – $12,206900 sq ft · 11.11 yd³ at 4 in
- 30x40 concrete slab cost$9,664 – $16,1061,200 sq ft · 14.81 yd³ at 4 in
Compare with the next sizes
Garage concrete slab cost calculatorAll slab sizes and the full calculator
Frequently asked questions
How much rebar does a 20x30 slab need?
The estimate uses 850 linear ft of rebar on a grid. Your engineer or local code may set a different spacing.
Is a 20x30 slab too big for DIY?
For most people, yes. At 7.41 yd³ the finishing window is short, and a crew with power trowels handles it faster.
Does a 20x30 garage slab need a vapor barrier?
Under a heated or finished space, yes. You can add one in the calculator's options to see the cost.
What's the cost per square foot for a 20x30 slab?
$8.31 – $13.84 at national prices. The rate usually drops a little as slabs get bigger, because setup is spread over more area.
For contractors
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