Concrete Footing and Wall Calculator

Enter the length, width and depth of a footing or the length, height and thickness of a wall and get the volume and the bags to buy, with the working shown. Volume only: it does not size a footing.

A ready-made setup of the Concrete Calculator.

Estimates for planning, not professional advice. Read the full notice.

Footing or wall size

Feet and inches, like 12' 6"

A footing's width, or a wall's height.

A footing's depth, or a wall's thickness.

Example: a footing run

66 80 lb bags

  • Concrete in the footing 35.56 ft³
  • To mix, with waste 39.11 ft³
  • To order as ready-mix 1.45 yd³

Estimate for planning, from what you entered and the product data shown. Check product labels and your supplier before you buy.

Shopping list

Example: a footing run
ItemSizeBuy
Concrete mix80 lb bag66

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    Worked example: a footing run

    Show the working
    1. Footing volume 40 ft × 1 ft 4 in × 8 in = 35.56 ft³
    2. Add the waste allowance 35.555556 ft³ + 10%[1] = 39.11 ft³
    3. Divide by the bag's yield 39.111111 ft³ ÷ approx. 0.6 ft³[2] = 65.19 bags
    4. Round up once, to whole bags 65.19 bags = 66 × 80 lb bags

    Assumptions

    The figures behind the example. Sourced figures link to their source below; a default is a starting value to check against your label or supplier.

    Concrete waste allowance 10%[1]
    Default 10% is the top of NRMCA's 4% to 10% range.
    Yield of the 40 lb bag approx. 0.3 ft³[2]
    A 40 lb bag of QUIKRETE Concrete Mix 1101 yields about this many cubic feet, as the maker's own sheet states.
    Yield of the 50 lb bag approx. 0.375 ft³[2]
    A 50 lb bag of QUIKRETE Concrete Mix 1101 yields about this many cubic feet, as the maker's own sheet states.
    Yield of the 60 lb bag approx. 0.45 ft³[2]
    A 60 lb bag of QUIKRETE Concrete Mix 1101 yields about this many cubic feet, as the maker's own sheet states.
    Yield of the 80 lb bag approx. 0.6 ft³[2]
    An 80 lb bag of QUIKRETE Concrete Mix 1101 yields about this many cubic feet, as the maker's own sheet states.
    Yield of the 90 lb bag approx. 0.675 ft³[2]
    A 90 lb bag of QUIKRETE Concrete Mix 1101 yields about this many cubic feet, as the maker's own sheet states.

    Bags for a ten foot run, by footing width and depth

    80 lb bags of concrete mix for a ten foot run of footing, by width and depth, with the waste allowance added

    Footing width6 in deep8 in deep12 in deep
    8 in 7 × 80 lb bags9 × 80 lb bags13 × 80 lb bags
    1 ft 10 × 80 lb bags13 × 80 lb bags19 × 80 lb bags
    1 ft 4 in 13 × 80 lb bags17 × 80 lb bags25 × 80 lb bags
    1 ft 8 in 16 × 80 lb bags21 × 80 lb bags31 × 80 lb bags
    2 ft 19 × 80 lb bags25 × 80 lb bags37 × 80 lb bags

    Each count is rounded up once, to whole bags, after the waste allowance is added. For a longer run, enter its length in the calculator rather than adding these counts. The bag yields come from QUIKRETE's published sheet. Product names are trademarks of their owners. HoneyDoMath is not affiliated with, sponsored by or endorsed by these makers.

    Questions

    How many bags of concrete for a 12 inch footing?

    Enter the length of the run, the width and the depth. The table on this page gives the bags for a ten foot run at common widths and depths, and the calculator counts any length.

    How is the concrete for a wall figured?

    A wall is its length times its height times its thickness. Put the height in the width field and the thickness in the depth field; the calculator adds the waste allowance and rounds up once, at the bag.

    Does the count include waste?

    Yes. The waste allowance sits in the assumptions above, starts at the top of the range the ready-mix industry body gives for ordering, and you can change it.

    Will a 4 inch footer hold a house?

    This calculator works out concrete volume only and does not size footings. What a footing needs depends on the load and the soil, so ask your local building department.

    Sources (2)
    1. CIP 31, Ordering Ready Mixed Concrete, National Ready Mixed Concrete Association, 2000, 2016, 2023. Standards or industry body
      “Quantity of concrete ordered should be 4% to 10% more than an estimate calculated from the plan dimensions to account for contingencies.”
      Checked November 12, 2026. Figures and codes change; verify with the source. Back to where this is used
    2. QUIKRETE Concrete Mix No. 1101 data sheet, The Quikrete Companies, Revised October 2022. Manufacturer data
      “An 80 lb (36.2 kg) bag yields approximately 0.60 ft3 (17 L)”
      “A 40 lb (18.1 kg) bag yields approximately 0.30 ft3 (8.5 L)”
      “A 50 lb (22.6 kg) bag yields approximately 0.375 ft3 (10.6 L)”
      “A 60 lb (27.2 kg) bag yields approximately 0.45 ft3 (12.7 L)”
      “A 90 lb (40.8 kg) bag yields approximately 0.675 ft3 (19.1 L)”
      Per QUIKRETE's data sheet, checked Nov 12, 2026. Figures and codes change; verify with the source. Back to where this is used

    These are summaries of what the sources say, not professional advice. Codes and product data change. Check with your building department and the product label about your own project.

    Sources

    • [1] National Ready Mixed Concrete Association, CIP 31, Ordering Ready Mixed Concrete. Checked November 12, 2026. https://www.nrmca.org/wp-content/uploads/2021/01/31pr.pdf
    • [2] QUIKRETE, QUIKRETE Concrete Mix No. 1101 data sheet. Checked November 12, 2026. https://www.quikrete.com/PDFs/DATA_SHEET-Concrete%20Mix%201101.pdf

    Made with HoneyDoMath.com. Estimates for planning; check product labels and local codes before you buy or build.