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How Much Concrete for 48 Feet of Footing?

How much concrete for 48 feet of footing depends on the footing’s width and depth. A common residential footing 16 inches wide by 8 inches deep works out to about 1.58 cubic yards over 48 feet, before waste.

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Footing math

  1. Cross-section: 16 in × 8 in = 1.333 ft × 0.667 ft = 0.889 sq ft.
  2. Volume: 0.889 × 48 ft = 42.7 cu ft.
  3. Yards: ÷ 27 = 1.58 yd³.

Yards for common footing sizes over 48 feet

Footing (width × depth)Cubic feetCubic yardsYards +10%
12 × 6 in24.00.890.98
16 × 8 in42.71.581.74
20 × 8 in53.31.982.17
24 × 10 in80.02.963.26
24 × 12 in96.03.563.91

Sizing and depth

Code and soil bearing decide the footing size. Light walls often sit on 12 to 16 inch wide footings, while two-story loads or weak soils call for wider ones. Whatever the size, the bottom has to reach undisturbed soil below frost depth. See footing depth and the frost line.

Trench pours run over

When the footing is poured straight into a dug trench instead of forms, the sides wander and the bottom is rarely flat. Measure the actual trench at several points and add 10 to 15 percent, not the usual 5.

Rebar and inspection

Footing steel is usually two or more horizontal bars held up off the soil. Book the inspection first, then the concrete: a failed inspection with a truck on the way is an expensive afternoon.

Questions people ask

How many yards for 48 feet of 16x8 footing?

About 1.58 cubic yards before waste.

How many yards for 48 feet of 24x12 footing?

About 3.56 cubic yards.

How much extra should I order for a trench footing?

About 10 to 15 percent, since trench walls are rarely straight.

How deep should a footing be?

Below the local frost line and on undisturbed soil; your building department sets the minimum.

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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