AsphaltTons.com — asphalt tonnage calculator

How Much Concrete for a 10x15 Slab?

For a 10x15 slab poured 4 inches thick, plan on about 1.85 cubic yards of concrete. That comes from 150 square feet times 0.333 feet of depth, divided by 27. How much concrete for a 10x15 slab at other thicknesses is in the table below.

Concrete calculator →

The math for a 10x15 slab

  1. Area: 10 ft × 15 ft = 150 sq ft.
  2. Thickness in feet: 4 in ÷ 12 = 0.333 ft.
  3. Volume: 150 × 0.333 = 50.0 cubic feet.
  4. Cubic yards: 50.0 ÷ 27 = 1.85 yd³.
  5. With 10% extra: 2.04 yd³.

The concrete calculator runs the same steps for any size and thickness.

Concrete for a 10x15 slab by thickness

ThicknessCubic feetCubic yardsYards +10%80 lb bags60 lb bags
4 in50.01.852.0484112
5 in62.52.312.55105139
6 in75.02.783.06125167

Bag counts assume about 0.60 cubic feet per 80 lb bag and 0.45 per 60 lb bag, rounded up.

Thickness for this job

Four inches is the usual thickness for patios, walks and shed floors. Slabs that carry cars or a heavy hot tub are often poured at 5 to 6 inches, and edges are sometimes thickened where loads concentrate.

Ordering ready-mix

Concrete is ordered by the cubic yard, and a yard is 27 cubic feet. Ready-mix plants usually sell in quarter- or half-yard steps, so round up to the next step rather than down. Running short in the middle of a pour leaves a cold joint, which is a weak seam in the slab.

Base and forms

Prep matters as much as the yardage. Strip sod and soft soil, compact the subgrade, then add a compacted stone base, commonly about 4 inches. A level, firm base also keeps your thickness even, which keeps the yardage close to the math.

Joints and reinforcement

Plan the joints before the pour. Panels close to square crack less than long, narrow ones, and joint spacing around 8 feet is typical for a 4-inch slab. Cut joints with a groover while the concrete is soft or with a saw within the first day.

Questions people ask

How many yards of concrete for a 10x15 slab at 4 inches?

About 1.85 cubic yards, or 2.04 with 10 percent extra.

How many yards for a 10x15 slab at 6 inches?

About 2.78 cubic yards.

How many 80 lb bags for a 10x15 slab?

About 84 bags at 4 inches thick, before any waste allowance.

How many square feet is a 10x15 slab?

150 square feet.

How much does a cubic yard of concrete weigh?

Roughly 4,000 pounds, or about 2 tons, for normal-weight concrete.

When is bagged concrete practical?

Usually for jobs under about a cubic yard. Beyond that, mixing dozens of bags by hand gets slow and batches may not blend well.

Related guides

Open the concrete calculator → Asphalt tonnage calculator →

As an Amazon Associate, AsphaltTons.com earns from qualifying purchases. Product links below are sponsored.

Related answers