Concrete Footing Calculator

Treat each footing as a rectangular prism

This calculator estimates concrete for a rectangular strip footing or multiple identical runs. Its formula is run length × width × depth × count. Convert the three dimensions to compatible units before multiplying. For example, a run measured in feet with width and depth in inches requires converting the inches to feet or using a consistent internal unit system.

If footing sections differ, calculate each group separately and add the volumes. A stepped footing, isolated pad, pier, or irregular excavation is not a rectangular strip; use its actual geometry or a suitable separate method. The count is for identical runs only.

The dimensions must come from the design

Footing width and depth are design inputs, not values the calculator recommends. Required dimensions can depend on loads, soil, frost, water, reinforcement and governing requirements. The calculator does not evaluate any of those conditions. Use the approved drawings and have questions resolved by the responsible design professional or authority.

The word “footing” can describe very different foundations. A simple rectangular volume may match an estimated quantity without matching the actual form, excavation, or concrete placement. The estimate is only as accurate as the dimensions and geometry entered.

Count separate runs carefully

List each continuous run and measure its centerline or specified length according to the project takeoff convention. Avoid counting intersections twice. If two strips cross, the volume at their overlap may be included in both rectangular prisms. Deduct the intersection once if the estimating method requires it, or follow the project’s established takeoff convention.

For multiple identical runs, verify that length, width, and depth truly match. If they do not, group similar runs and calculate each group separately. Record each segment and unit so an estimator or supplier can review the basis.

Add ordering allowance deliberately

The calculator applies the entered percentage to the geometric total. This is a transparent planning allowance, not a correction for poor measurements or a recommendation about waste. Excavation may be irregular and concrete may occupy additional space, but the correct reserve depends on site and delivery conditions. Ask the concrete supplier or contractor how they handle overrun and truck quantities.

Do not use the estimate to set reinforcement, concrete strength, mix type, or excavation safety. These require project specifications and suitable professional direction. The tool measures quantity from dimensions; it does not design a foundation.

A takeoff should identify each run on the plan, especially at corners and intersections. Include a note if your convention counts intersecting strips as separate pours or deducts their overlap. That small record prevents different people from comparing totals that used different geometric assumptions.

Coordinate supply and placement

After checking dimensions against the plans, share the volume and assumptions with the supplier. Confirm the concrete mix specification, order increments, access, discharge method, placement sequence, and timing with the project team. Concrete placement must be coordinated with the crew and delivery; the calculated total alone does not determine a feasible pour.

For bagged materials, divide by the selected product’s stated yield and round up. For ready-mix, use the supplier’s ordering guidance and confirm the delivery ticket’s units. Retain the plan reference and measured runs with the estimate so any revision is traceable.

For a continuous strip with branches, sketch the sequence and identify the junction. A volume total should correspond to a clear construction quantity, not merely the sum of every line visible on a drawing.