8x8 Concrete Slab, 4 Inches Thick
Poured 4 in thick, a 8 × 8 ft slab covering 64 sq ft needs about 0.87 cubic yards of concrete once 10% is added for waste. For ready-mix, order 1 cu yd for the 8x8, about $200 – $290 delivered, short-load fee included. Bagged, the same 8x8 is 40 80 lb or 53 60 lb bags, about $265 – $371 for the concrete alone.
- Ready-mix order
- 1 cu yd
- Ready-mix cost
- $200 – $290
- 80 lb bags
- 40
- Bag cost
- $265 – $371
Materials only for a 8x8 at 4 in, from national price ranges as of 2026-09; not a live quote.
What fits on an 8x8 slab
An 8 by 8 square is about the smallest pad that holds a garden shed, a grill station with a little elbow room, or a fire-pit seating spot for two chairs.
Most 8x8 storage sheds sit right on a pad that matches their footprint, so the shed walls land on the slab edge; a pad an inch or two bigger on each side keeps the sill plate from hanging over.
People also pour 8x8 for a small hot tub, but a tub that is already 7 to 8 ft across leaves no walking room and no place for steps, so most hot-tub owners go a size or two larger.
A 4 in 8x8 pour: check first
- Measure the shed floor frame, not the roof overhang, when sizing the pad.
- Set anchor bolts in the wet concrete if the shed kit calls for them; drilling later works too but costs more.
- Leave a gravel strip around the pad so splashback from the roof doesn't rot the siding.
Full plan for a 8x8 slab, 4 in
- Area
- 64 sq ft
- Thickness
- 4 in
- Volume
- 0.87 cu yd
Bagged concrete estimate (DIY)
$327 – $472
Est. as of 2026-09 — not a live quote
Ready-mix delivered, incl. short-load fee (materials only)
$200 – $290
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 79 × 40 lb, 63 × 50 lb or 40 × 80 lb bags. 53 bags
- Ready-mix concrete Alternative to bagged mix; most suppliers have a 1 cu yd order minimum. 1 cu yd
- Compactable gravel sub-base 4 in compacted base beneath the slab. 1.07 tons
- 6x6 welded wire mesh Reinforcement for crack control; not a substitute for engineered rebar on structural slabs. 71 sq ft
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Assumptions
- Waste allowance: 10% applied to account for over-excavation and spillage.
- Approx. wet weight: 3,520 lb (1.8 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 8x8 slab, 4 in?
23.5 cu ft for a 8x8 is still workable in bags: 40 80 lb bags is a few hours of mixing, and a rented drum mixer makes it easier. Ready-mix has a 1 cu yd minimum, about 13% more than the 8x8 needs, plus a short-load fee, so it costs $200 – $290 against $265 – $371 in bags. The bag and ready-mix ranges overlap on a 4 in 8x8, so call one supplier about 1 cu yd and check the shelf price of 40 bags before you choose.
Is 4 in thick enough for a 8x8 slab?
4 in is the usual thickness for a 8x8 patio, walkway, shed floor or equipment pad that carries foot traffic.
Control joints for a 8x8 slab at 4 in
Like any slab, a 4 in 8x8 shrinks while it cures; control joints decide where its cracks go. The usual rule (ACI and PCA guidance) puts joints in a 8x8 at 4 in every 8 to 12 ft, 24 to 36 times the thickness, cut 1 in deep (a quarter of the thickness) as soon as the surface takes the saw without raveling, usually within the first day.
No side of a 8x8 slab is longer than 10 ft, so at 4 in it can go without an interior joint. Tool one across the middle of the 8x8 anyway if you want a straight line for any crack to follow.
How much a 8x8 slab 4 in thick weighs
At roughly 150 lb per cubic foot of wet concrete, a 8x8 at 4 in puts about 3,520 lb (1.8 tons) on the ground. As bags, the 8x8 is 40 80 lb bags, 3,200 lb in all: about 3 trips in a pickup carrying 1,500 lb a load. For that many trips with the 8x8, check the payload on your truck's door-jamb sticker, or have the store deliver the pallets for a fee.
The 8x8 at 4 in against nearby sizes
Every row uses the same 10% waste and prices as the 8x8 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 |
|---|---|---|---|---|---|---|
| 4x4 slab, 4 in | 0.22 | 14 | 10 | 1 cu yd | $70 – $98 | $200 – $290 |
| 8x8 slab, 4 in (this page) | 0.87 | 53 | 40 | 1 cu yd | $265 – $371 | $200 – $290 |
| 8x10 slab, 4 in | 1.09 | 66 | 49 | 1.25 cu yd | $330 – $462 | $235 – $335 |
Questions about a 8x8 slab, 4 in
How many bags of concrete for a 8x8 slab 4 inches thick?
A 8x8 slab at 4 in takes about 40 80 lb bags or 53 60 lb bags (or 63 50 lb, 79 40 lb), with 10% added for waste: 23.5 cubic feet in all.
How many yards of concrete for a 8x8 slab 4 inches thick?
0.87 cubic yards with waste (0.79 without) for a 8x8 at 4 in. Round the 8x8 order to 1 cu yd: plants batch in quarter yards and most won't send less than a yard.
How much does a 8x8 concrete slab 4 inches thick cost?
Concrete alone for the 8x8 runs about $200 – $290 for 1 cu yd of ready-mix delivered, short-load fee included, or $265 – $371 for 53 60 lb bags. Add a 4 in gravel base and wire mesh and the bagged 8x8 plan comes to $327 – $472. Labor, forms and finishing for a 8x8 at 4 in come on top of these national ranges (as of 2026-09), which are not quotes.
How much does a 8x8 concrete slab 4 inches thick weigh?
About 3,520 lb (1.8 tons) of wet concrete for the 8x8, at 150 lb per cubic foot. The 40 80 lb bags for a 8x8 weigh 3,200 lb: about 3 trips in a pickup carrying 1,500 lb a load.
Where do control joints go on a 8x8 slab 4 inches thick?
On a 8x8 at 4 in, every 8 to 12 ft (24 to 36 times the thickness), sawn 1 in deep. No side of a 8x8 slab is longer than 10 ft, so at 4 in it can go without an interior joint. Tool one across the middle of the 8x8 anyway if you want a straight line for any crack to follow.
Limitations
The 8x8 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 8x8 slab with a qualified professional.