HomeMath

Concrete Wall Calculator

A poured concrete wall 20 ft long, 4 ft high and 8 in thick on a 16 × 8 in footing takes 2.90 cu yd of concrete with 10% waste, 1.98 cu yd in the wall and 0.66 cu yd in the footing. Enter the wall's and the footing's sizes to get the yards of each, the 40, 60 and 80 lb bags, the ready-mix order, the cost at your price per yard and a check of the footing against the code's minimum size. For a cinder block wall it sizes the footing alone.

Units
What you pour
Wall thickness preset
Footing preset

2.90 cu yd (78.22 cu ft) of concrete

Wall, before waste:
1.98 cu yd (53.33 cu ft)
Footing, before waste:
0.66 cu yd (17.78 cu ft)
Cubic feet:
78.22 cu ft
Without the waste allowance:
2.63 cu yd (71.11 cu ft)
Ready-mix order:
3.00 cu yd
80 lb bags:
131 bags
60 lb bags:
174 bags
40 lb bags:
261 bags
Concrete cost at your price:
$450 for the order, before delivery
Footing against the code minimum:
meets IRC R403.1.1's minimum size
Poured retaining wall installed, 80 sq ft of face:
about $2,400–$4,800 (Concrete Network $30–$60 per sq ft; Fixr $2,400–$3,200)

Example price only: type your plant's. Code minimum by IRC R403.1.1; installed ranges from Concrete Network and Fixr, read October 2026.

How HomeMath calculates a concrete wall and its footing

HomeMath treats the wall and the footing as two boxes along the same length. The wall is length × height × thickness, the footing length × width × depth, each in feet, and the two add up to the pour; ÷ 27 gives cubic yards. The height is the wall above the footing, so nothing is counted twice. The waste allowance (10% to start) goes on the total, bags are rounded up, and the order to the next quarter yard. The footing check centers the wall on the footing: the projection is (footing width − wall thickness) ÷ 2. In metric, HomeMath converts meters and centimeters exactly (1 in = 2.54 cm) and shows the result in cubic meters, liters and square meters.

The published rules it uses: US customary units; metric conversion; premixed bag yields; footing minimums; foundation and wall prices. Their sources, and how HomeMath tests every result, are on the about page.

How much concrete do common walls take?

With 10% waste, wall and footing together.

  • Garden retaining wall 20 ft × 3 ft × 8 in, 16 × 8 in footing2.35 cu yd · order 2.50 yd
  • Stem wall 120 ft × 2 ft × 8 in, 16 × 8 in footing10.86 cu yd · order 11.00 yd
  • Basement wall 140 ft × 8 ft × 8 in, 16 × 8 in footing35.49 cu yd · order 35.50 yd
  • Basement wall 140 ft × 8 ft × 10 in, 20 × 10 in footing45.95 cu yd · order 46.00 yd
  • Footing for a 40 ft cinder block wall, 16 × 8 in1.45 cu yd · order 1.50 yd
  • Footing for a 60 ft block wall, 12 × 6 in1.22 cu yd · order 1.25 yd

How much concrete does a wall and its footing take?

  1. Convert inches to feet: an 8 in wall is 8 ÷ 12 = 0.667 ft, a 16 × 8 in footing 1.333 × 0.667 ft.
  2. Wall: 20 × 4 × 0.667 = 53.33 cu ft.
  3. Footing: 20 × 1.333 × 0.667 = 17.78 cu ft.
  4. Together 71.11 cu ft ÷ 27 = 2.63 cu yd, or 2.90 cu yd with 10% waste: order 3.00 yd, or 131 bags of 80 lb.

How much concrete is in each foot of wall?

Multiply by the wall's length for its concrete before the footing and waste. A cubic yard is 27 cubic feet.

Cubic feet of concrete per foot of wall length
Wall2 ft high3 ft high4 ft high6 ft high8 ft high
6 in thick1.00 cu ft1.50 cu ft2.00 cu ft3.00 cu ft4.00 cu ft
8 in thick1.33 cu ft2.00 cu ft2.67 cu ft4.00 cu ft5.33 cu ft
10 in thick1.67 cu ft2.50 cu ft3.33 cu ft5.00 cu ft6.67 cu ft
12 in thick2.00 cu ft3.00 cu ft4.00 cu ft6.00 cu ft8.00 cu ft

How thick should a concrete wall be?

Type the thickness your plans give; the calculator has presets of 6, 8, 10, 12 in. Thickness changes the concrete in a straight line: a 10 in wall takes 25% more than an 8 in wall of the same size, and a 12 in wall 50% more.

How wide and deep should the footing be?

The International Residential Code sets the minimum in R403.1.1: at least 12 in wide and 6 in thick, with a projection past the wall of at least 2 in and no more than the footing's thickness. Its tables ask for more under heavier houses and weaker soil, and the footing goes below your frost line, so your plans and local code set the real size.

The narrowest code-minimum footing, and the widest a 6 in footing allows
Wall thicknessMinimum footingWidest at 6 in thick
6 in12 × 6 in18 in
8 in12 × 6 in20 in
10 in14 × 6 in22 in
12 in16 × 6 in24 in

A wider footing must also be thicker: a 24 in footing under an 8 in wall projects 8 in, so it needs 8 in of depth.

How much concrete goes under a cinder block wall?

A block wall is laid in mortar on a poured footing. Pick "Footing for a block wall", type the wall's length and the block's width (8 in for a standard 8 × 8 × 16 in block), and the calculator pours only the footing. A 40 ft footing 16 × 8 in takes 1.45 cu yd with 10% waste. Count the blocks in the concrete block calculator.

Concrete per foot of footing, and the feet one cubic yard pours
Footing (width × depth)Per footFeet per cu yd
12 × 6 in0.50 cu ft54.0 ft
16 × 8 in0.89 cu ft30.4 ft
20 × 8 in1.11 cu ft24.3 ft
20 × 10 in1.39 cu ft19.4 ft
24 × 12 in2.00 cu ft13.5 ft

How much concrete does a stem wall or basement wall take?

For a foundation, type the building's perimeter, 2 × (length + width), as the wall length: 180 ft for a 40 × 50 ft house. An 8 in stem wall 2 ft high takes 8.89 cu yd before its footing. A basement wall 8 ft high and 8 in thick takes 41.48 cu yd with a 16 × 8 in footing, before waste, which is about 1,867 bags of 80 lb: a job for several trucks. To price the whole foundation installed, use the concrete foundation cost calculator.

How much does a poured concrete retaining wall cost?

Concrete Network puts a basic poured retaining wall at $30–$60 per square foot of face (updated June 26, 2020) and Fixr at $30–$40 (updated January 31, 2025), with the footing, forms, steel and labor. A wall 20 ft long and 4 ft high is 80 sq ft, so $2,400–$4,800 at the first and $2,400–$3,200 at the second.

Poured concrete retaining walls installed, by face size
Wall (length × height)Concrete NetworkFixr
10 × 3 ft (30 sq ft)$900–$1,800$900–$1,200
20 × 3 ft (60 sq ft)$1,800–$3,600$1,800–$2,400
20 × 4 ft (80 sq ft)$2,400–$4,800$2,400–$3,200
40 × 4 ft (160 sq ft)$4,800–$9,600$4,800–$6,400
50 × 6 ft (300 sq ft)$9,000–$18,000$9,000–$12,000

Its footing is often wider, toward the soil it holds back, and curves, steps, finishes and drainage add to the price. Fixr advises a structural engineer for walls over 4 ft, and Concrete Network notes that walls over 4 ft are usually poured in two phases, footing first.

What does the concrete for a poured wall cost?

For the material, multiply the order by your plant's price per yard; Concrete Network's ready-mix range is $160–$195 a cubic yard before delivery. The 3.00 yd order above is $480–$585 at that range. A small order may carry a short-load fee; price it with delivery and labor in the concrete cost calculator.

Frequently asked questions

How much concrete do I need for a wall?
Multiply length × height × thickness in feet and divide by 27. A 20 ft wall 4 ft high and 8 in thick is 20 × 4 × 0.667 = 53.33 cu ft, or 1.98 cu yd; its 16 × 8 in footing adds 0.66 cu yd, so order 3.00 yd with 10% waste.
What size footing do I need for a cinder block wall?
At least 12 in wide and 6 in thick by the International Residential Code (R403.1.1), and wide enough to project 2 in or more on each side of the wall: under an 8 in block wall, 12 in is the minimum. The code's tables ask for more under a heavier house or on weaker soil, and your plans and local code set the real size.
How much concrete goes in a footing under a block wall?
1.45 cu yd for a 40 ft footing 16 in wide and 8 in deep with 10% waste, or 66 bags of 80 lb mix. Pick "Footing for a block wall" and the calculator pours only the footing; count the blocks on top in the concrete block calculator.
How wide and deep should a concrete footing be?
By the code minimum, 12 in wide and 6 in thick, with a projection past the wall of at least 2 in and no more than the footing's thickness: a 16 in footing under an 8 in wall projects 4 in each side, so its depth must be at least 4 in, which the 6 in minimum already covers. The footing also sits below the frost line, which your local code gives.
How much does a poured concrete retaining wall cost?
$30–$60 per square foot of wall face for a basic poured wall, by Concrete Network (updated June 26, 2020), and $30–$40 by Fixr (updated January 31, 2025). A wall 20 ft long and 4 ft high is 80 sq ft, so about $2,400–$4,800. Curves, steps, decorative finishes, drainage and an engineer raise it.
How do I calculate the cost of a concrete wall?
For the concrete alone, multiply the order in cubic yards by your plant's price per yard: the 20 ft wall's 3.00 yd at $150 a yard is $450 before delivery, and Concrete Network's ready-mix range is $160–$195 a yard. Forms, rebar, labor and a pump come on top; the installed range covers them all.
How thick should a concrete wall be?
As thick as your plans and local code say; taller walls and walls holding back more soil need more. Thickness changes the concrete in a straight line: a 10 in wall takes 25% more than an 8 in wall of the same size, and a 12 in wall 50% more. A retaining wall's thickness, footing and steel come from its design, and Fixr advises a structural engineer for walls over 4 ft.
How much concrete does a stem wall or basement wall take?
The same math for any poured wall: length × height × thickness, plus the footing. For a foundation, the length is the building's perimeter: a 40 × 50 ft house has 180 ft of wall, so an 8 in stem wall 2 ft high takes 8.89 cu yd before its footing. Type the perimeter as the wall length.
How do I calculate concrete for a wall in cubic meters?
Multiply length × height × thickness in meters: a 6 m wall 1.2 m high and 20 cm thick is 6 × 1.2 × 0.20 = 1.44 m³, and a 40 × 20 cm footing under it adds 6 × 0.40 × 0.20 = 0.48 m³. Switch the calculator to metric to enter meters and centimeters.
Does the calculator include rebar or forms?
No, it measures the concrete. Rebar takes a little room in the wall, so the volume holds a small margin; forms, ties, rebar and the pump are in the installed price or in your own list. The concrete cost calculator prices a pour with delivery and labor if you need more lines.

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