BuildCalc

Concrete Wall Calculator

Estimate the concrete for a poured wall — a foundation wall, stem wall, retaining wall or basement wall. Enter the length, height and thickness and the calculator returns the cubic yards, the bag count and the rebar for a 16 inch grid.

Concrete for the wall
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    How it works

    Volume (cu ft) = length × height × (thickness ÷ 12); cubic yards = cu ft ÷ 27. Rebar assumes a single curtain on a 16 in on-centre grid running both ways. 80 lb bags = cubic feet ÷ 0.60, rounded up — though a wall of any size is a ready-mix job, not a bag job.

    Frequently asked questions

    How much concrete do I need for a wall?

    Multiply length × height × thickness in feet, then divide by 27. A 20 ft long, 8 ft tall, 8 in thick wall is 20 × 8 × 0.667 = 106.7 cubic feet, or about 3.95 cubic yards before waste.

    How thick should a poured concrete wall be?

    Residential foundation and basement walls are commonly 8 inches, sometimes 10 or 12 where backfill is deep or the wall carries more load. Retaining walls are engineered to the height and soil. Follow local code.

    Can I pour a concrete wall with bags?

    In practice, no. A modest 20 ft wall is about 4 cubic yards — roughly 180 bags of 80 lb. Walls are a ready-mix job; the bag figure is shown only to give a sense of scale.

    How much rebar does a concrete wall need?

    A common residential pattern is #4 bar on a 16 in grid in one curtain, with extra bars at corners and openings. This calculator estimates the linear feet for that grid. Reinforcement in a structural or retaining wall must come from an engineer or your code.

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    Estimates are for planning only. Material yields, densities and code requirements vary — confirm quantities with your supplier and local building code before ordering.