Foundation Material Estimator

Concrete Footing Calculator

Estimate concrete for continuous wall footings, garage footings, shed footings, and deck beam footings. Enter run length, width, depth, and number of runs to get cubic yards, bags, waste, and material cost.

Footing Runs
Handles one or more identical continuous footing sections.
Cross Section
Uses footing width and depth for rectangular trench volume.
Bags or Yards
Converts concrete volume into bags and ready-mix yardage.

Enter Footing Dimensions

Raw footing volume before waste

1 run / 17.78 ft3 / 0.66 yd3

Results

Concrete Volume

0.7243 yd³

19.5556 ft³ / 0.5538 m³

Bags Needed

33 bags

Rounded up to whole bags

Estimated Cost

$165.00

Based on bag price

Waste Factor

10%

Included in total volume

Formula

One footing run

Volume per run = length x width x depthVolume per run = 20 x 1.333 x 0.667

All runs

Raw volume = volume per run x runsRaw volume = 17.7778 before waste

Waste and bags

Final volume = 17.7778 x (1 + 10%/100)Bags = ceil(final volume / 0.6)

Example Footing Estimates

20 ft wall footing

One 16 in wide x 8 in deep continuous footing.

Result: 0.7243 yd3 / 19.5556 ft3 / 33 bags

Two 24 ft garage runs

Two footing runs, each 18 in wide x 10 in deep.

Result: 2.4444 yd3 / 66 ft3 / 110 bags

12 ft shed footing

One smaller 12 in wide x 8 in deep footing run.

Result: 0.3259 yd3 / 8.8 ft3 / 15 bags

Footing Size Notes

TopicNote
Footing widthDepends on load, soil bearing capacity, wall thickness, and local code.
Footing depthMay need to reach below frost depth or suitable bearing material.
ReinforcementRebar size and placement are design details, not material volume assumptions.
Trench conditionUneven excavation can increase concrete volume beyond the clean rectangle.

Before You Pour

  • Measure the actual trench dimensions after excavation.
  • Calculate different footing sizes separately, then add them.
  • Keep over-excavation, loose sidewalls, and bottom irregularity in mind.
  • Confirm inspection, reinforcement, and local code requirements before scheduling concrete.

Frequently Asked Questions

How do I calculate concrete for a footing?
For a continuous footing, multiply length by width by depth after converting all measurements to the same unit. Multiply by the number of identical runs, then add waste before ordering concrete.
What is a footing run?
A run is one straight footing section with the same length, width, and depth. If you have four identical sides, enter 4 runs and the length of one side. For different lengths, calculate each group separately and add the totals.
How much waste should I add for footings?
A 10% waste factor is a practical default. Use more for uneven trenches, loose soil, over-excavation, wet conditions, or formwork that is not perfectly consistent.
Does this calculator design footing size?
No. It estimates concrete volume only. Footing width, depth, reinforcement, frost depth, bearing soil, loads, and local code requirements should be confirmed with a qualified professional.
Should I use bags or ready-mix for footings?
Small deck or shed footings may be reasonable with bags. Longer wall or garage footings can require many bags, so compare the bag count with local ready-mix delivery minimums.

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Concrete Volume CalculatorConcrete Slab CalculatorConcrete Bag CalculatorConcrete Steps CalculatorConcrete Cost CalculatorReady-Mix vs Bags Calculator

Disclaimer: This calculator estimates concrete material volume only. It does not design footing size, bearing capacity, reinforcement, frost protection, drainage, or code compliance. Consult a qualified contractor, engineer, or local building department for structural footing requirements.