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How Much Concrete for a 10x25 Slab?

For a 10x25 slab poured 4 inches thick, plan on about 3.09 cubic yards of concrete. That comes from 250 square feet times 0.333 feet of depth, divided by 27. How much concrete for a 10x25 slab at other thicknesses is in the table below.

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The math for a 10x25 slab

  1. Area: 10 ft × 25 ft = 250 sq ft.
  2. Thickness in feet: 4 in ÷ 12 = 0.333 ft.
  3. Volume: 250 × 0.333 = 83.3 cubic feet.
  4. Cubic yards: 83.3 ÷ 27 = 3.09 yd³.
  5. With 10% extra: 3.40 yd³.

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

Concrete for a 10x25 slab by thickness

ThicknessCubic feetCubic yardsYards +10%80 lb bags60 lb bags
4 in83.33.093.40139186
5 in104.23.864.24174232
6 in125.04.635.09209278

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

How thick to pour it

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

A cubic yard of concrete is 27 cubic feet and weighs roughly 4,000 pounds. Most ready-mix trucks carry up to about 9 to 10 yards, though local trucks and rules vary. If your total is under a yard or two, bagged mix or a short-load supplier may be cheaper.

Prep before the pour

Under the slab, most residential pours sit on about 4 inches of compacted gravel. The base spreads the load, drains water away and keeps the slab from cracking as the soil freezes and thaws. Compact the base in thin lifts, and dampen it just before the pour so it does not pull water out of the mix.

Joints, mesh and rebar

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 10x25 slab at 4 inches?

About 3.09 cubic yards, or 3.40 with 10 percent extra.

How many yards for a 10x25 slab at 6 inches?

About 4.63 cubic yards.

How many 80 lb bags for a 10x25 slab?

About 139 bags at 4 inches thick, before any waste allowance.

How many square feet is a 10x25 slab?

250 square feet.

How many 80 lb bags make a cubic yard?

About 45. Each 80 lb bag yields roughly 0.6 cubic feet, and a cubic yard is 27 cubic feet.

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.

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