Concrete Wall Calculator

How to calculate concrete for a wall

A poured wall is a rectangular box: length × height × thickness. Measure length and height in feet and thickness in inches, then convert to cubic yards, the unit ready-mix is sold in.

Cubic feet = length (ft) × height (ft) × thickness (in) ÷ 12
Cubic yards = cubic feet ÷ 27

The calculator above runs the same math and returns cubic yards, cubic feet, cubic meters and bag counts, with a waste allowance (10% by default).

1. Measure the wall length along its centreline. For a wall that turns a corner, add the legs, but count the corner block only once.
2. Measure the height of the pour, from the top of the footing to the top of the wall, not from the ground.
3. Use the form thickness, the inside distance between the form faces.
4. Subtract openings for windows, doors and pipe sleeves, measured as height × width × wall thickness.
5. Add 10% for forms that bow under the weight of wet concrete, spillage and an uneven footing top.

How much concrete per foot of wall?

Most walls are a standard thickness and a known height, so a per-foot figure is the fastest way to estimate. This table gives the volume per 10 ft of wall length for each foot of height, and per linear foot of a full 8 ft wall. All figures come from the site’s calculation library.

To use it, multiply the second column by your length in tens of feet and by your height in feet. A 30 ft wall 5 ft high at 10 in is 3 × 5 × 0.309 = 4.63 yd³. The last column is 324 ÷ thickness in inches: the same shortcut used for slabs, turned on its side.

How much concrete for common wall sizes?

This table covers walls people search for most, from a short garden wall to a full basement. The order column adds 10% and rounds up to the next quarter yard; check the increment your ready-mix plant sells in. Bag counts include the 10% extra and use QUIKRETE’s published yields of 0.60 ft³ per 80 lb bag and 0.45 ft³ per 60 lb bag.

The bag columns show why poured walls are mostly ready-mix jobs. Anything past a yard runs to dozens of bags, and a wall poured in batches risks cold joints where one batch sets before the next arrives. Bagged mix makes sense for short garden walls and repairs. The concrete bag calculator covers bag counts in more detail.

Concrete retaining walls: what the calculator does and does not do

The calculator gives the volume of concrete for the wall dimensions you enter. It does not design the wall. A retaining wall holds back soil and water, and its thickness, height, footing, drainage and reinforcement must come from a design: a structural engineer’s drawings, a manufacturer’s system or your local building department’s requirements.

Once you have that design, the calculator is the right tool for the quantity. Enter the stem dimensions here, size the footing on the concrete footing calculator, and add the two. Many retaining wall designs use a stem that tapers or a footing with a heel and toe; split those into rectangles and add each one.

QUIKRETE’s data sheet lists foundation walls among the uses for its Concrete Mix and rates it at 4,000 psi at 28 days under ASTM C39 testing. Whether that or a ready-mix design strength is what your wall needs is again a question for the design, not this page.

If you would rather build the wall from concrete block, the concrete block calculator counts the blocks and core fill, and the mortar calculator turns the block count into bags of mortar mix.

How to include the footing and openings

A wall pour often includes the footing, and a basement wall always has openings. Work each piece out separately and add or subtract.

• Footing: length × width × depth. A continuous footing 16 in wide and 8 in deep under a 30 ft wall is 30 × 1.333 × 0.667 = 26.67 ft³, or 0.99 yd³.
• Openings: height × width × wall thickness for each window or door. Two 3 × 4 ft windows in an 8 in wall remove 2 × 3 × 4 × 0.667 = 16 ft³.
• Pilasters and corners: treat a pilaster as a small column and add it; at corners, measure one wall to the outside face and the other to the inside face so the corner is not counted twice.

Stepped, sloped and tapered walls

Walls on sloping ground rarely have one height along their whole length. Split them into pieces the calculator can handle and add the results.

• Stepped wall: work out each step as its own rectangle. A 40 ft wall, 8 in thick, with 20 ft at 4 ft high and 20 ft at 2 ft high is 53.33 + 26.67 = 80 ft³, or 2.96 yd³. With 10% extra that is 3.26 yd³, so order 3.5 yd³.
• Sloped top: use the average height. A 40 ft wall that falls evenly from 4 ft to 2 ft has an average height of 3 ft, so it is 40 × 3 × 0.667 = 80 ft³, the same 2.96 yd³. Using the 4 ft maximum instead would give 3.95 yd³, a yard too much.
• Tapered wall: use the average thickness. A 20 × 4 ft wall that is 12 in thick at the bottom and 8 in at the top averages 10 in: 66.67 ft³, or 2.47 yd³, against 2.96 yd³ if you priced it at the full 12 in.

Whether a wall should step, slope or taper is a design choice. These rules only turn the shape you have been given into a volume.

Ordering ready-mix for a wall pour

Ready-mix in the US is usually ordered in cubic yards. Ask your plant what increment it sells in; the order column in the size table rounds up to the next quarter yard after the 10% allowance. Ask your plant how it sells part loads and what it charges for a small load; that varies by plant and area.

Walls are poured in lifts around the form so the concrete rises evenly on both sides. Tell the plant it is a wall pour, give them the total volume and the access for the truck, and ask whether you need a pump or a chute extension to reach the forms. The concrete itself is the same volume either way; the delivery method changes how fast it arrives.

Have a plan for any concrete left over, such as a small pad or a set of forms for stepping stones. Ten percent extra on a 20 yd³ basement wall is 2 yd³, and it has to go somewhere before it sets.

Concrete wall volume in metric

In metric, multiply length × height × thickness, all in metres, and the answer is cubic metres. There is no conversion step.

• A 10 m wall, 2.4 m high and 200 mm thick: 10 × 2.4 × 0.2 = 4.8 m³, or 5.28 m³ with 10% extra (about 6.28 yd³ before the extra).
• A 6 m garden wall, 1 m high and 250 mm thick: 6 × 1 × 0.25 = 1.5 m³, or 1.65 m³ with 10% extra.

If your plans are in metric but the plant sells in cubic yards, convert at the end: 1 m³ is about 1.31 yd³, so the 4.8 m³ wall above is about 6.28 yd³. Keep the unit the supplier uses for the final order, and round up rather than down after the conversion.

Each square metre of wall face takes 0.15 m³ at 150 mm thick, 0.2 m³ at 200 mm and 0.25 m³ at 250 mm. Switch the calculator to metric to enter dimensions in metres and centimetres.

How much does a concrete wall weigh?

The site uses 150 lb/ft³ for normal-weight concrete, the unit weight WSDOT uses for plain concrete (FHWA gives a 140–155 lb/ft³ range, and WSDOT uses 155 lb/ft³ with reinforcement); QUIKRETE lists about 140 lb/ft³ for its bagged Concrete Mix. At 150 lb/ft³, each square foot of wall face weighs 100 lb at 8 in thick and 150 lb at 12 in. A 10 × 4 ft wall 8 in thick weighs about 4,000 lb; a 100 × 8 ft basement wall 8 in thick, about 80,000 lb.

That weight is why forms need bracing and why a footing must be designed for the wall it carries. It also matters for anything you plan to demolish or haul away later.

Common mistakes when calculating concrete for a wall

Most wall-pour errors come from units and from forgetting parts of the pour.

• Entering thickness in feet. An 8 in wall typed as 8 ft makes a 20 × 4 ft wall 640 ft³ instead of 53.33 ft³, twelve times too much.
• Leaving out the footing. On the 30 ft example, the footing is 0.99 of 3.95 yd³, a quarter of the pour.
• Measuring height from the ground. Walls usually start on a footing below grade. Measure the formed height, footing top to wall top.
• Ordering the exact volume. Forms bulge and footing tops are rarely flat. Without the 10% allowance, a 1.98 yd³ wall leaves no margin, and a short load on a wall pour can leave a cold joint.
• Double-counting corners. On a 24 × 24 ft basement, measuring all four walls to the outside face adds four corner blocks of concrete that are not there.
• Treating the calculator as a design. Height limits, thickness and reinforcement for retaining and foundation walls come from an engineer or local code, not from a volume formula.

Concrete wall calculator vs footing, block and slab calculators: which one to use

This page sizes poured concrete walls: foundation walls, stem walls and the stem of a designed retaining wall. Use a different tool for the rest of the job:

• Concrete footing calculator: the continuous footing under the wall, or pier footings.
• Concrete block calculator: a wall built from 8 × 8 × 16 in blocks instead of poured, with core fill.
• Rebar calculator: bar counts and weights for reinforcing, once the design gives a spacing.
• Concrete bag calculator: 40, 50, 60, 80 and 90 lb bag counts for small walls.
• Concrete yards calculator: adding up several shapes into one ready-mix order.