10x20 Concrete Slab, 4 Inches Thick
Poured 4 in thick, a 10 × 20 ft slab covering 200 sq ft needs about 2.72 cubic yards of concrete once 10% is added for waste. For ready-mix, order 2.75 cu yd for the 10x20, about $445 – $605 delivered, short-load fee included. Bagged, the same 10x20 is 123 80 lb or 163 60 lb bags, about $815 – $1,141 for the concrete alone.
- Ready-mix order
- 2.75 cu yd
- Ready-mix cost
- $445 – $605
- 80 lb bags
- 123
- Bag cost
- $815 – $1,141
Materials only for a 10x20 at 4 in, from national price ranges as of 2026-09; not a live quote.
Jobs that call for a 10x20 slab
Ten by twenty feet is about the size of one parking space, so this slab is often a parking pad for a car, a small trailer or a boat on its trailer.
It also makes a long, narrow patio along the back of a house, or the floor of a 10x20 carport or lean-to off a garage.
Because it is twice as long as it is wide, a 10x20 needs at least one joint across the middle, or it tends to crack there on its own.
Before you pour the 10x20 at 4 in
- If it will carry a car, make sure the base is well compacted at the end where the wheels roll on and off.
- Slope a parking pad toward the street or a drain; slope a patio version away from the house.
- Check how close to the property line a parking pad can sit in your town.
Full plan for a 10x20 slab, 4 in
- Area
- 200 sq ft
- Thickness
- 4 in
- Volume
- 2.72 cu yd
Bagged concrete estimate (DIY)
$1,009 – $1,456
Est. as of 2026-09 — not a live quote
Ready-mix delivered, incl. short-load fee (materials only)
$445 – $605
Est. as of 2026-09 — not a live quote
For a pour this size, ready-mix delivery is typically more practical than mixing bags by hand.
Shopping list
- Concrete mix (60 lb bags) Or 245 × 40 lb, 196 × 50 lb or 123 × 80 lb bags. 163 bags
- Ready-mix concrete Alternative to bagged mix; most suppliers have a 1 cu yd order minimum. 2.75 cu yd
- Compactable gravel sub-base 4 in compacted base beneath the slab. 3.33 tons
- 6x6 welded wire mesh Reinforcement for crack control; not a substitute for engineered rebar on structural slabs. 220 sq ft
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Buy bagged concrete
Pick up bagged mix and reinforcement from a hardware store for smaller pours.
View shopping listAssumptions
- Waste allowance: 10% applied to account for over-excavation and spillage.
- Approx. wet weight: 11,000 lb (5.5 tons).
- Prices are national-average retail/delivery ranges as of 2026-09, not live quotes.
- Ready-mix orders under 10 cu yd usually carry a short-load fee; the ready-mix range includes a flat $60-$110. Some suppliers charge per yard instead, so ask for the full fee schedule.
Bags or ready-mix for a 10x20 slab, 4 in?
A 10x20 at 4 in lands in the 1 to 3 cubic yard range, where bags and ready-mix cost about the same. For the 10x20, 123 80 lb bags cost about $815 – $1,141, while 2.75 cu yd of ready-mix costs about $445 – $605, short-load fee included. On the 10x20, ready-mix comes out cheaper by about $453 at the middle of each range, and it saves mixing 123 bags.
Is 4 in thick enough for a 10x20 slab?
Foot traffic, patio furniture and a shed all sit fine on a 10x20 poured 4 in thick, the standard for slabs that don't carry vehicles.
Control joints for a 10x20 slab at 4 in
A 10x20 slab at 4 in shrinks as it cures, and without joints it cracks wherever it chooses. ACI and PCA guidance spaces joints 24 to 36 times the thickness, which for this 10x20 at 4 in is every 8 to 12 ft, sawn 1 in deep (a quarter of the slab) once the surface holds up to the blade, usually within a day.
On the 10x20 at 4 in, a joint every 10 ft or less means 1 joint across the 20 ft side and 0 joints across the 10 ft side: 2 panels of about 10 × 10 ft and 10 ft of saw cut. The 10x20 is 2 times as long as it is wide, and long, narrow slabs crack across their width, so don't skip its cross joints.
How much a 10x20 slab 4 in thick weighs
At roughly 150 lb per cubic foot of wet concrete, a 10x20 at 4 in puts about 11,000 lb (5.5 tons) on the ground. As bags, the 10x20 is 123 80 lb bags, 9,840 lb in all: about 7 trips in a pickup carrying 1,500 lb a load. Nobody hauls 9,840 lb of bags for a 10x20 in a pickup; it comes by ready-mix truck or as pallets on a delivery truck.
The 10x20 at 4 in against nearby sizes
Every row uses the same 10% waste and prices as the 10x20 at 4 in; costs are for the concrete only.
| Slab | Cu yd | 60 lb bags | 80 lb bags | Ready-mix order | Bags cost | Ready-mix cost |
|---|---|---|---|---|---|---|
| 14x14 slab, 4 in | 2.66 | 160 | 120 | 2.75 cu yd | $800 – $1,120 | $445 – $605 |
| 10x20 slab, 4 in (this page) | 2.72 | 163 | 123 | 2.75 cu yd | $815 – $1,141 | $445 – $605 |
| 12x20 slab, 4 in | 3.26 | 196 | 147 | 3.5 cu yd | $980 – $1,372 | $550 – $740 |
Questions about a 10x20 slab, 4 in
How many bags of concrete for a 10x20 slab 4 inches thick?
Plan on 73.3 cubic feet for the 10x20, which is 123 80 lb bags, 163 60 lb bags, 196 50 lb or 245 40 lb bags once 10% waste is in.
How many yards of concrete for a 10x20 slab 4 inches thick?
The 10x20 measures out at 2.47 cubic yards, or 2.72 with 10% for waste. Order 2.75 cu yd for the 10x20, since ready-mix is sold in quarter yards with a 1 yard minimum at most plants.
How much does a 10x20 concrete slab 4 inches thick cost?
Concrete alone for the 10x20 runs about $445 – $605 for 2.75 cu yd of ready-mix delivered, short-load fee included, or $815 – $1,141 for 163 60 lb bags. Add a 4 in gravel base and wire mesh and the bagged 10x20 plan comes to $1,009 – $1,456. Labor, forms and finishing for a 10x20 at 4 in come on top of these national ranges (as of 2026-09), which are not quotes.
How much does a 10x20 concrete slab 4 inches thick weigh?
About 11,000 lb (5.5 tons) of wet concrete for the 10x20, at 150 lb per cubic foot. The 123 80 lb bags for a 10x20 weigh 9,840 lb: about 7 trips in a pickup carrying 1,500 lb a load.
Where do control joints go on a 10x20 slab 4 inches thick?
On a 10x20 at 4 in, every 8 to 12 ft (24 to 36 times the thickness), sawn 1 in deep. On the 10x20 at 4 in, a joint every 10 ft or less means 1 joint across the 20 ft side and 0 joints across the 10 ft side: 2 panels of about 10 × 10 ft and 10 ft of saw cut.
Limitations
The 10x20 figures at 4 in are material estimates and typical price ranges, not a quote or a structural design. Confirm that 4 in, the reinforcement and the joint layout suit your soil, loads and local code for a 10x20 slab with a qualified professional.