DeckPlan Tools
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Deck Footing Calculator

Convert user-defined footing geometry into concrete volume and bag quantities. Change any input to see an immediate, explainable estimate.

Project inputs

in
in
cu ft
%
Add cutting and defect allowance; complex layouts often need more.

Plan preview

Interactive deck plan10 by 10 foot rectangle deck, length boards, showing boards view.10 ft10 ftSCALED TO FIT
Accessible summary: 0 ft long × 0 ft wide; standard layout. Drawing is for planning visualization, not construction details.

Your estimate

Updates live
Concrete bags26
Concrete with waste15.55 cu ft
Cubic yards0.58
Volume per footing2.36 cu ft
Assumptions
  • 6 identical round footings
  • 0.6 cu ft yield per bag
This estimates concrete only; it does not select footing count, size, depth, or reinforcement.

How to use this calculator

  1. Measure the project and enter the requested dimensions. Use actual product dimensions where the form asks for them.
  2. Replace the sample assumptions with the spacing, stock lengths, coverage, or prices that apply to your plan.
  3. Review the result, assumptions, and any limitation notice. Save the project locally or export a dated PDF for discussion.
Quantity estimate—not structural approval.

This calculator does not verify loads, spans, soil, frost depth, connections, product approvals, or local code. Use a qualified local professional for decisions that affect safety.

Calculation methodology

Round footings use cylinder volume; rectangular footings use length × width × depth. Total volume plus waste is divided by the entered bag yield and rounded up.

Intermediate values retain decimal precision. Physical purchase units are rounded up only at the purchasing step, so the tool does not silently understate whole boards, bags, boxes, or containers.

Worked example

Six 12 in diameter × 36 in deep cylinders require about 14.1 cu ft before waste; the bag count depends on the package yield you enter.

Material and measurement considerations

  • Use the yield printed on the concrete package.
  • Excavations are rarely perfect shapes.
  • Footing dimensions and frost depth need local design input.

Common mistakes

  • Using diameter as radius.
  • Mixing inches and feet.
  • Selecting footing dimensions from this quantity tool.

Frequently asked questions

How deep should my footings be?

This calculator does not specify depth. Soil, loads, frost conditions, and local requirements control the design.

Sources and limitations

The estimator uses your measurements, standard geometry, unit conversion, and product data you enter. Product coverage, gaps, fastening, and installation details should come from the current manufacturer documentation for the exact material. Structural and permit requirements must be confirmed for the project location. No live price feed, fabricated standard, or universal structural rule is used.