Concrete Wall Calculator

The formula

Volume = Length × Height × Thickness. Convert to cubic yards (1 yd³ = 27 ft³). Bags = volume in ft³ ÷ bag yield (80-lb ≈ 0.6 ft³).

How to estimate concrete for a concrete wall

A poured concrete wall is sized like a vertical slab: length times height times thickness. A typical residential foundation wall is 8 inches thick, though 6, 10, and 12 inches are all common depending on the height of backfill and the load above. Because thickness is in inches and the wall face is in feet, divide the thickness by 12 first — or let the calculator handle it. Enter the dimensions and you get the concrete in cubic yards and in 40, 60, and 80-lb bags.

Walls are almost always a ready-mix job, not a bag job. Even a small wall runs into multiple cubic yards — a 10-foot, 8-foot-tall, 8-inch wall is about 2 cubic yards, which is well over a hundred 80-lb bags. The calculator shows the bag counts for completeness, but past about half a cubic yard, ordering ready-mix by the truck is far cheaper and the only practical way to place a continuous wall before it starts to set.

A poured wall is structural, so the concrete is only part of it. The wall sits on a footing (size it with the footing calculator), carries vertical and horizontal rebar to a schedule set by code or an engineer, and needs braced forms that can take the pressure of wet concrete. Order about 10% extra, and confirm the wall thickness, footing, and reinforcement for your situation before you pour.

Frequently asked questions

How much concrete do I need for a wall?+

Multiply the wall length × height × thickness (in feet) for cubic feet, then divide by 27 for cubic yards. A 10-foot-long, 8-foot-tall, 8-inch-thick wall is about 53 cubic feet, or 2 cubic yards — roughly 2.2 with overage. Enter your dimensions above for an exact figure.

How thick should a concrete wall be?+

A common residential foundation wall is 8 inches thick, with 6, 10, and 12 inches used depending on the wall height, the backfill, and the load above. Thickness is a structural decision — confirm it against your local code or an engineer.

How many bags of concrete for a wall?+

Far more than you want to mix by hand — an 80-lb bag yields about 0.6 cubic feet, so a 2-cubic-yard wall is over 90 bags. Walls are a ready-mix job; the calculator shows the bag count, but order by the cubic yard.

How many cubic yards of concrete in a wall?+

Length × height × thickness ÷ 27. A 20-foot wall, 8 feet tall and 8 inches thick, is about 4 cubic yards. The calculator gives the exact yards plus a 10% overage figure.

Do concrete walls need rebar?+

Yes — poured structural walls carry vertical and horizontal rebar sized and spaced per code or an engineer. The calculator estimates concrete volume only; confirm the rebar schedule for your wall.

What goes under a concrete wall?+

A concrete footing, poured first, that spreads the wall load onto the soil. Size it with the concrete footing calculator. The footing usually sits on firm undisturbed soil or a compacted crushed-stone base.

Should I use bags or ready-mix for a wall?+

Ready-mix, in nearly all cases. A continuous wall must be placed before it sets, which is impractical with bags past about half a cubic yard, and ready-mix is cheaper per yard. Bags only make sense for a tiny stem wall or a patch.

How much extra concrete should I order for a wall?+

About 10%. Forms bulge slightly, and you cannot stop a continuous pour to mix more, so a little over is essential. The calculator includes an adjustable overage.

How is a concrete wall different from a block wall?+

A poured (cast-in-place) wall is solid concrete placed in forms; a block wall is built from stacked concrete masonry units (CMU) and mortar. Use this calculator for poured walls and the concrete block calculator for block walls.

Is this concrete wall calculator free?+

Yes — free, no sign-up, and it runs entirely in your browser, so nothing you enter is stored or sent anywhere.