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MaterialCalc — Concrete Patio Slab Cost Calculator

Estimate prepared 09/01/2026. Estimates only; verify against your plans before ordering.

Concrete Patio Slab Cost Calculator

Four inches is plenty for furniture and foot traffic.

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Result

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A patio is the one slab where 4 inches is genuinely enough — it carries furniture and people, not vehicles, so the money is better spent on the base and the finish than on thickness. A typical 16x12 patio is about two cubic yards, which sits right on the line between bagging it and ordering a truck.

Assumptions used

These are the numbers behind the result. Where one of them is soft, the cost range widens rather than pretending to a precision the data does not have.

80 lb bag yield
0.6 ft³

Yield of one 80 lb bag of standard concrete mix.

Quikrete product data sheet — Published product data, checked 09/01/2026

60 lb bag yield
0.45 ft³

Yield of one 60 lb bag of standard concrete mix.

Quikrete product data sheet — Published product data, checked 09/01/2026

Ready-mix short-load threshold
1 yd³

Below roughly one cubic yard, most suppliers add a short-load fee that erases the price advantage over bags.

Regional ready-mix supplier schedules — Rough figure — widens the estimate range, checked 09/01/2026

Bags per pallet
42 bags

Above roughly one pallet of 80 lb bags, ready-mix is usually cheaper and always faster.

Home Depot / Lowe's pallet quantities — Industry standard, varies by supplier, checked 09/01/2026

Compacted gravel base under slab
4 in

Drains water away from the underside of the slab. Skipping it is the usual cause of a slab that heaves.

International Residential Code (2021) — Industry standard, varies by supplier, checked 09/01/2026

Crushed gravel density
105 lb/ft³

Compacted 3/4 in crushed stone. Varies by quarry and moisture; loose stone runs lighter.

USGS aggregate bulk density range — Industry standard, varies by supplier, checked 09/01/2026

Compaction allowance
0.2

Loose stone loses roughly a fifth of its volume once compacted, so order above the finished volume.

Standard earthwork practice — Rough figure — widens the estimate range, checked 09/01/2026

Vapor barrier roll coverage
1000 ft²

Home Depot / Lowe's published product data — Published product data, checked 09/01/2026

Welded wire mesh sheet coverage
150 ft²

One 5x10 ft sheet, less the overlap at the seams.

Home Depot / Lowe's published product data — Industry standard, varies by supplier, checked 09/01/2026

Prices verified 09/01/2026 (US national average, big-box retail shelf price and regional ready-mix quotes). Regional adjustment: Blended from RSMeans city cost index bands and BLS construction wage differentials.

The formula

Area × thickness ÷ 27 = cubic yards. A 16x12 patio at 4 in is 192 ft² × 0.333 ft = 64 ft³ = 2.37 yd³ before waste. The gravel base is the same calculation at 4 in, converted to tons at about 105 lb per cubic foot.

Worked examples

16x12 patio at 4 in

Patio length: 16 Patio width: 12 Thickness: 4 Waste: 10

About 2.6 cubic yards with waste. Just past the short-load threshold, so ready-mix is worth pricing against roughly 100 bags.

10x10 patio at 4 in

Patio length: 10 Patio width: 10 Thickness: 4 Waste: 10

About 1.4 yards. Small enough that the short-load fee dominates, and small enough that a strong crew can genuinely bag it in a day.

20x16 patio at 4 in

Patio length: 20 Patio width: 16 Thickness: 4 Waste: 10

Roughly 4.3 yards. Comfortably a truck job, and big enough that you want a finisher rather than doing it yourself.

Choosing materials

  • Slope away from the house, a quarter inch per foot. A patio that drains toward the foundation is worse than no patio, and the slope has to be built into the base — you cannot fix it with concrete thickness.
  • Two cubic yards is the awkward size. Bagging it is 90 bags and a brutal weekend; ordering it means paying a short-load fee. Price both in the comparison table before deciding.
  • A broom finish is standard and is the right call. Smooth troweled concrete outdoors is dangerously slick when wet, and stamped finishes cost two to three times as much.
  • Control joints every 8 to 10 feet on a patio, cut within a day of the pour. On a 16x12 that is one cut across the short dimension.
  • If you might build a roof or pergola over it later, decide now. Post footings are simple to pour with the slab and miserable to retrofit through finished concrete.

Common questions

How much concrete for a 16x12 patio?

At 4 inches thick, 2.37 cubic yards before waste, or about 2.6 with a 10% allowance. That is around 107 bags of 80 lb mix, which is why most people order ready-mix at this size.

How thick should a concrete patio be?

Four inches. A patio carries people and furniture, and the extra cost of 5 or 6 inches buys nothing you will notice. Spend the difference on a properly compacted base instead — that is what stops cracking.

What does a concrete patio cost?

Material for a 16x12 patio typically runs $600 to $950 including base and mesh. Poured and finished by a contractor, expect roughly $1,700 to $2,900. Stamped or colored finishes roughly double the labor figure.

Concrete patio or pavers?

Concrete is cheaper per square foot and faster to install. Pavers cost more up front but individual units can be lifted and reset if the ground settles, and they never crack in a straight line across the middle. If your soil moves, pavers age better.

Do I need gravel under a patio slab?

Yes, four inches of compacted crushed stone. It is the single biggest factor in whether the slab is still flat in ten years, and on a patio it costs a fraction of what the concrete does.

How long before I can use a new patio?

Walk on it after 24 to 48 hours. Put furniture on it after a week. Keep it damp for the first few days in hot weather — concrete that dries too fast at the surface crazes and dusts.

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