How Much Does a 4 Inch Concrete Slab Cost
A 4-inch slab is the default for patios, shed floors, walkways, and garage slabs, and it is also the cheapest thickness to pour. But the '4 inch' label hides a wide price range, because the finish, your region, and the site conditions move the number as much as the thickness does. This guide gives you the 2026 per-square-foot ranges, puts a 4-inch slab head-to-head with a 6-inch one so you can see what the upgrade actually buys, and totals it up for the sizes homeowners ask about most.
What the per-square-foot price includes
A contractor's square-foot number normally bundles the gravel base, forming, reinforcement, the concrete, placement, finishing, and control joints. It usually excludes tearing out an old slab, drainage structures, and permits. Ask each bidder to itemize those so you are comparing the same scope. Material is roughly 35-45% of the total; labor is the rest, which is why prices track local wage rates more than the price of cement.
4-inch slab cost per square foot (2026)
These are typical installed ranges for a broom- or smooth-finished 4-inch slab by finish quality:
| Finish | Installed cost per sq ft (2026) |
|---|---|
| Plain broom finish | $6 - $12 |
| Smooth troweled finish | $7 - $13 |
| Exposed aggregate | $10 - $18 |
| Colored / integrally tinted | $11 - $19 |
| Stamped decorative | $14 - $26 |
4 inch vs. 6 inch: the real comparison
Most homeowners only debate 4 vs. 6 inches. The concrete volume at 6 inches is 1.5 times the 4-inch amount, so material and labor both scale — but the price per square foot does not quite triple because finishing and base prep stay similar. Here is the trade-off:
| Factor | 4-inch slab | 6-inch slab |
|---|---|---|
| Concrete per 100 sq ft | 1.23 cu yd | 1.85 cu yd |
| Best for | Patios, walks, sheds, light foot traffic | Driveways, RV pads, garages, light vehicles |
| Installed cost per sq ft | $6 - $14 | $9 - $20 |
| 400 sq ft total | $2,400 - $5,600 | $3,600 - $8,000 |
| Reinforcement | Wire mesh usually enough | Rebar grid recommended |
| Frost / load performance | Adequate for foot traffic | Better for vehicle and freeze-thaw |
Go 6 inches if anything heavier than a riding mower will sit on it, or if you are in a severe freeze-thaw climate where the extra mass resists cracking. Stay at 4 inches for pure foot-traffic patios and shed floors to keep the budget down. For a slab that doubles as a wall footing or a step base, the block calculator can size adjoining masonry.
Total cost by slab size
Concrete volume for that 576 sq ft garage at 4 inches is 576 x (4/12) / 27 = 7.1 cubic yards before waste, about 7.8 yards with 10%.
What pushes the price up
- Demolition: removing an old slab adds $2 - $6 per square foot.
- Base prep: soft soil may need over-excavation and imported fill before the gravel.
- Reinforcement: a #4 rebar grid adds roughly $0.80 - $2.00 per square foot over wire mesh.
- Slope and drainage: anything past a mild grade needs forming labor or a trench drain.
- Sealing: optional in mild climates, about $0.50 - $1.50 per square foot every few years in freeze-thaw zones.
Concrete vs. the alternatives
Pavers run $15 - $30 per square foot and are the most repairable; asphalt is cheaper up front but shorter-lived. Poured concrete sits in the middle and typically lasts 30+ years with joint maintenance, which is why it stays the default for sheds and patios. If you are weighing a brick border or a brick-look finish, the brick calculator will show the real material cost before you decide.
Get an accurate number
Measure your footprint, pick the thickness from the table above, and add 10% for waste. Enter it all into the Concrete Slab Calculator for cubic yards, bag counts, and a cost estimate you can take to three local bids.