MyYardCalc
Construction · Material planning

Concrete Calculator

Calculate concrete volume for slabs, footings and round or hollow columns. Estimate ready-mix yardage and bags using the labeled mixed yield.

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Your project

US & metric

Example values are filled in. Replace them with your measurements.

ft
ft
ft
in
%

An editable purchasing margin, not a measured compaction rate.

cu ft

Use the mixed yield printed on your concrete bag.

lb / cu yd

Optional. Enter the density of this product to estimate weight.

$
$ / cu yd
$

Enter 0 if included. Bulk cost remains blank until delivery is specified.

Enter your measurements

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The calculation

Volume = net area × depth × (1 + extra ÷ 100). Weight = volume × supplier density.

  • Enter your supplier’s bulk density to show weight. Volume alone cannot determine tons.
  • 10% extra is included once. Confirm supplier minimums and delivery increments.

Saved on this device

Only estimates you choose to save are stored here.

    Measure with a little context

    How to use this concrete calculator

    Select the geometry of the pour and enter actual dimensions. For columns, the thickness field represents the full column height.

    Bag quantities use mixed yield, not dry bag volume or weight. Confirm ready-mix minimums and delivery charges before ordering.

    Volume = net area × depth × (1 + extra ÷ 100). Weight = volume × supplier density.

    A worked example

    With the example values shown below, the calculated result is 1.304 cu yd. These are demonstration inputs, not installation specifications.

    View the example measurements
    • Length / outside diameter: 12 ft
    • Width: 8 ft
    • Inside diameter: 1 ft
    • Identical pours: 1
    • Thickness / column height: 4 in
    • Extra allowance: 10 %
    • Yield per bag: 0.6 cu ft

    From estimate to order

    Whole packages and pieces round up; measured lengths, areas and volumes keep full precision during calculation. Match the product dimensions and units to your quote, and check cuts, minimum orders and delivery before purchasing.

    Read our formulas, rounding rules and limitations →

    A bag of cement is not a bag of concrete mix

    Cement is one ingredient in concrete. A bag of ready-to-mix concrete contains a specified blend; its label states the volume of concrete it produces after mixing. Enter that mixed yield in the bag field. Do not enter the bag's weight or use the same yield for a cement-only bag.

    For example, 0.5 m³ equals 500 litres. A product yielding 12 litres per bag requires 500 ÷ 12 = 41.667, rounded up to 42 bags before allowance. If a chosen 5% reserve is needed, calculate 500 × 1.05 ÷ 12 = 43.75 and buy 44 bags. Avoid rounding each intermediate figure.

    For site-mixed concrete, obtain a specified mix and calculate its ingredients separately. This volume tool does not design a cement:sand:aggregate ratio or water-cement ratio. The concrete bag guide compares example mixed yields; the rebar calculator handles a separately specified reinforcement grid.

    Concrete planning questions

    How do I convert concrete yards to bags?

    Multiply cubic yards by 27 for cubic feet, then divide by the mixed yield printed on the bag and round up. The yield is the volume of prepared concrete, not the dry bag volume or bag weight. Different products and bag sizes have different yields.

    How do I calculate a round column or hollow cylinder?

    Select the corresponding pour shape and enter the outside diameter. A hollow cylinder also needs the inside diameter. The thickness or column-height field uses inches in US mode or centimeters in metric mode, so convert a full column height before entering it.

    How many 80 lb bags of concrete are in a cubic yard?

    Use the mixed yield on the actual product label. If an 80 lb bag yields 0.60 cubic feet, 27 ÷ 0.60 = 45 bags supply one cubic yard before allowance. Bag weight alone is not enough to guarantee that yield. Other mix types and bag sizes can have different yields.

    Calculation notes updated . Formulas, sources and limitations.

    Keep your project moving.

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