FootingCalc

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Concrete Footing Calculator

Enter your footing dimensions and total length — get cubic yards, bags, and cost instantly. Contractor-grade math with the formula shown, not a black box.

Footing dimensions

Measuring run by run? Use the linear feet of footing calculator to add wall segments first.

Concrete needed

10.19 YD³
Cubic feet275.00
Cubic meters7.79
Bags (80 lb)459
Est. ready-mix cost$1,681.25

Includes your waste allowance. Ready-mix pricing varies by region and load size — confirm with your local plant. Bag counts are rounded up.

Doing whole plans, not single runs?

FootingTakeoff reads a footing plan and returns total linear feet, pad count, and an invoice at your rates — automatically.

See FootingTakeoff

How this calculator works

Footing volume is a rectangular prism: width × depth × length. The only trick is unit discipline — width and depth are measured in inches on plans, length in feet:

ft³ = (width in ÷ 12) × (depth in ÷ 12) × length ft
yd³ = ft³ ÷ 27   ·   bags = ft³ ÷ yield per bag (80 lb ≈ 0.60 ft³)

Example: a 20″ × 6″ footing running 300 LF is (1.667 × 0.5 × 300) = 250 ft³ = 9.26 yd³, call it 10.2 yd³ with 10% waste. That's a ready-mix order, not a bag job — 250 ft³ would take more than 400 eighty-pound bags.

Typical residential footing sizes

Most house wall footings run 16–24 inches wide and 6–12 inches thick depending on soil and load. See the full footing size chart for common configurations and code minimums, and always pour to your approved plans.

All tools

Every footing calculator on one site.

LF

Linear feet of footing

Add wall segments run by run, get total LF and an invoice-style total at your $/LF rate.

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Footing cost calculator

Concrete, per-linear-foot rates, and pads — a full footing cost estimate.

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Pad calculator

Interior support pads: volume, bags, and flat-rate billing per pad.

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Deck footing calculator

Sonotube and pier footings: concrete per tube and per project.

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Footing size chart

Common residential footing dimensions and code minimums, referenced.

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How to measure linear feet

The 5-minute method for measuring footing runs off a plan.

FAQ

Footing concrete questions, answered.

How do I calculate concrete for footings?
Multiply the footing width by its depth (both converted to feet) by the total length in feet to get cubic feet, then divide by 27 for cubic yards. Example: a 20 inch wide by 6 inch deep footing running 300 feet is (20/12) x (6/12) x 300 = 250 cubic feet = 9.26 cubic yards before waste. Add 5-10% waste for over-dig and spillage.
How many bags of concrete do I need for a footing?
Divide the footing volume in cubic feet by the yield per bag: an 80 lb bag yields about 0.60 cubic feet, a 60 lb bag about 0.45 cubic feet. Bagged concrete only makes sense for very small footings — beyond roughly one cubic yard (45 x 80 lb bags), ready-mix is cheaper and far less work.
What size are residential concrete footings?
Common residential wall footings are 16 to 24 inches wide and 6 to 12 inches thick, with 18-20 inches wide by 6-8 inches thick typical under 8-10 inch basement walls. Requirements depend on soil bearing capacity and local code, so always follow your approved plans.
Should I order ready-mix or mix bags for footings?
For anything over about one cubic yard, order ready-mix: a full house footing run of 250-350 linear feet is typically 8-12 cubic yards, which is a truck order, not a bag job. Use bag counts only for small pads, short runs, and repairs.