How Much Does a 12x12 Concrete Slab Cost?
A 12x12 concrete slab costs $864–1,728 installed at $6–12 per square foot, though contractor minimums often set the real floor. At 144 square feet it's the standard size for a shed base, a hot tub pad, or a small patio, and it takes 1.96 cubic yards at 4 inches with waste — small enough that bagged concrete and a short ready-mix load are both on the table.
A 12x12 concrete slab costs $864–1,728 installed — 144 square feet at the typical $6–12 per square foot. On a pad this small, the per-foot rate tells only half the story: most contractors apply a $500–800 minimum for mobilizing a crew and ordering a partial load, so quotes cluster toward the middle and top of the range. Check your size and region in the concrete cost calculator.
What a 12x12 Slab Is Usually For
- Shed base. A 12x12 fits the popular 10x12 and 12x12 sheds with a little apron. The shed base cost calculator prices shed pads at $6–11 per sq ft installed.
- Hot tub pad. Most residential hot tubs fit on a 12x12 with room for steps and a cover lifter. Check the manufacturer's pad spec before you form.
- Small patio. Room for a bistro set or a grill station. For decorative finishes, the patio cost calculator adds stamped and colored options.
All three are 4-inch slabs in the normal case, which clears the 3.5-inch IRC R506.1 minimum. Go to 6 inches for a heavy hot tub or an outdoor kitchen; see the patio thickness guide.
Bagged vs. Ready-Mix at 144 Square Feet
A 12x12 sits right where the two ways of buying concrete overlap:
| Thickness | Cubic Yards (exact) | With 10% Waste | 80-lb Bags | Bagged at $5.50–8.00/bag | Ready-Mix at $165–205/yd |
|---|---|---|---|---|---|
| 4 in | 1.78 | 1.96 | 89 | $490–712 | $323–401 |
| 5 in | 2.22 | 2.44 | 110 | $605–880 | $403–501 |
| 6 in | 2.67 | 2.93 | 132 | $726–1,056 | $484–601 |
Ready-mix wins on price even after the $50–100 short-load fee most plants charge on orders under 3–4 yards: $373–501 delivered for a 4-inch slab versus $490–712 in bags. Bags win only when a truck can't get within chute or wheelbarrow reach. Mixing 89 bags by hand is also a full day's work, with a real risk of cold joints between batches. The concrete cost per yard guide covers short-load pricing in detail.
12x12 Slab Cost in Four Cities
These ranges come from our patio cost by city data at 144 square feet:
| Metro | Installed $/sq ft | 12x12 Slab (144 sq ft) |
|---|---|---|
| Orlando, FL | $5.78–11.87 | $832–1,709 |
| San Francisco, CA | $5.94–15.78 | $855–2,272 |
| Raleigh, NC | $7.05–14.90 | $1,015–2,146 |
| Philadelphia, PA | $7.86–15.19 | $1,132–2,187 |
Base, Rebar, and Joints
- Gravel base: 4 inches of compacted stone under 144 sq ft is 1.78 cubic yards — about 2.5 tons, $44–89 at $25–50 per yard.
- Rebar: #3 bar at 18 inches each way is about 9 bars in each direction, roughly 216 linear feet ($162–324). Wire mesh is a common alternative for a shed or patio pad.
- Control joints: One joint each way at 6 feet makes four 6x6 panels. A 12-foot span without joints is past the 8–12-foot limit for a 4-inch slab.
- Permits: Many jurisdictions exempt small patios and sheds up to 120–200 square feet, and a 12x12 is 144 — above the lower threshold. See permit requirements.
DIY vs. Contractor for a 12x12 Slab
This is one of the best sizes to do yourself. Materials for a 4-inch slab run roughly $580–910: ready-mix delivered ($373–501), gravel ($44–89), and rebar ($162–324), plus forming lumber. Against $864–1,728 installed — and contractor minimums that push small jobs toward the top — the saving is often a third or more. Two people can place and finish 144 square feet comfortably. Our small concrete slab guide walks through the pour.
Need more room? The 10x20 slab cost covers a large shed or a parking pad.