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What Is a Concrete Calculator?

A concrete calculator is a tool that converts the physical dimensions of what you’re pouring — length, width, depth, or diameter — into the volume of concrete you’ll need to fill it. Concrete is bought by volume, typically in cubic yards for ready-mix delivery or by the bag for smaller pours, so the calculator’s job is to take measurements you already have (usually in feet and inches) and turn them into a number you can actually order against.

A good concrete calculator does three things:

  1. Converts dimensions to volume — length × width × depth for rectangular pours, or the equivalent formula for round columns and stairs.
  2. Accounts for waste — real-world pours rarely use exactly the calculated volume, due to subgrade irregularities, over-excavation, and spillage.
  3. Translates volume into an order — either the number of bags of premix you’ll need, or the cost of a ready-mix delivery at your local price per yard.

How to Use This Concrete Calculator

  • Pick your shape. Choose Slab, Footing, Round Column, or Stairs from the tabs above, depending on what you’re pouring.
  • Enter your measurements. Use feet and inches as marked — you don’t need to convert anything yourself.
  • Set your quantity. If you’re pouring more than one identical footing or column, enter the count and the calculator multiplies automatically.
  • Choose a waste factor. 5% is a reasonable default for most jobs; bump it up for uneven subgrade or a first-time pour location.
  • Pick bag size or enter your ready-mix price. The calculator shows both bag count and an estimated ready-mix cost side by side, so you can compare which route makes more sense for the size of the pour.
  • Read your results. Cubic feet, cubic yards, bags needed, and estimated cost update instantly as you adjust any input.

Free tool

Concrete calculator

Estimate concrete volume, ready-mix cost, and bag count for slabs, footings, columns, and stairs.

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Enter dimensions greater than 0 to calculate.

Volume (cubic feet)

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Volume (cubic yards)

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Bags needed

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Estimated ready-mix cost

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See how Buildend tracks material takeoffs to budget →

Estimate only. Actual concrete needs vary with subgrade prep, forming tolerances, and mix design. Confirm quantities with your ready-mix supplier before ordering.

Disclaimer: The calculators, assessments, and checklists on this page are provided by Buildend for general informational and planning purposes only. They are not a substitute for professional advice from a licensed engineer, accountant, attorney, or other qualified professional, and they should not be relied upon as the sole basis for any financial, structural, contractual, or safety-related decision. Results are estimates based on the values you enter and standard industry formulas or assumptions. They do not account for site-specific conditions, local building codes, contract terms, material specifications, or other factors that may materially affect actual outcomes. Buildend makes no warranty, express or implied, as to the accuracy, completeness, or applicability of any result produced by these tools. You are solely responsible for verifying all calculations, quantities, and figures with appropriate professionals — including your ready-mix supplier, structural engineer, accountant, and legal counsel — before relying on them for bidding, ordering materials, structural design, or contractual purposes. To the fullest extent permitted by law, Buildend disclaims all liability for any loss, damage, or claim arising from the use of, or reliance on, these tools.