Footings
Concrete Footing Calculator
A footing is a buried beam. Width and depth are often in inches, and the run is in feet. The tool keeps those units apart.
Your region
Feet, inches, cubic yards, and 40–80 lb bags
Concrete Calculator
Example measurements — replace them with yours.
Common sizes
Most orders add 5–10% for spillage, uneven ground, and the last bit left in the chute.
Cost, truck size, and concrete weight
Leave a price blank to skip that estimate. Use the number your supplier quoted.
This job
Add each pour — slab, piers, steps — and Concrete Calculator totals them.
How to use a concrete footing calculator
A footing is a buried beam. Continuous footings follow the wall. Spread footings under posts are short rectangles. Width and depth often live in inches on the drawing while the run is in feet — Concrete Calculator keeps those units apart so you do not multiply 16 × 8 × 40 as if every number were feet.
Footing size is a structural decision. This page only turns a size you already have into yards and bags. Soft soil, frost depth, and loads belong on the plan. “Footer” in search means the same pour as footing on most US jobs.
Worked example with the concrete footing calculator
Cross section = 1.333 ft × 0.667 ft = 0.89 ft². Times 20 ft = 17.8 ft³ = 0.66 yd³ neat. With 10% ≈ 0.72 yd³. That is still a bag-or-short-load decision for a single wall; a full house perimeter adds up fast.
Per foot of wall: 0.89 ft³ ≈ 0.033 yd³. Multiply by the trench length for a quick takeoff. A 120 ft perimeter of the same section is about 4.0 yd³ neat before waste. Re-run the Concrete Footing Calculator after thickness changes — depth moves yardage faster than length.
- 16×8 in → 0.89 ft³ per foot of length
- 12×12 in → 1.00 ft³ per foot
- 24×12 in → 2.00 ft³ per foot
Trenches, stone, and bells
If stone fills the bottom of the trench, concrete depth is less than dig depth — measure the pour depth. Collapsed trench sides grow volume; re-measure after digging instead of hoping a 10% waste line covers a cave-in. Round pier bells are extra — add them as spread footings or switch to the sonotube calculator for the tube and a separate pad for the bell.
Common mistakes
Multiplying 16 × 8 × 20 without converting inches.
- Using hole depth instead of concrete depth when stone fills the bottom.
- Collapsing trench sides — measure again before you order; a percentage cannot fix a cave-in.
- Mixing continuous wall footings and isolated pads into one average size.
Bags, yards, or a truck?
Single spread footings are often bags. A full foundation pour is a truck. Add each wall as its own pour if sizes change. Stem walls on top belong on the wall calculator.
The formula Concrete Calculator uses
ft³ = length × width × depth in feet. Round bags up; round truck orders to 0.25 yd.
Who this is for
Builders taking off continuous footings.
DIY deck pier caps (or switch to sonotube for round piers).
Foundation calculator takeoffs
A foundation calculator search often means continuous footings plus stem walls. Size the footing here and the wall on the wall calculator. Spread footings under posts are short rectangles with the same formula — length may only be a few feet.
Concrete footer calculator typos point at the same pour. Re-measure after digging. Cave-ins and over-excavation change yards more than a waste slider can honestly cover.
Related calculators and guides
Open the pages that match the next question on the job — volume is only the first number.
- Sonotube calculator for round piers
- Wall calculator
- Post hole calculator
- How to calculate yards
- Monolithic slab calculator
Frequently asked questions
How do I calculate concrete for a footing?
Convert width and depth to feet, multiply by length, divide by 27.
How much extra for footings?
10% is a reasonable default for trenches. Re-measure after digging.
Continuous vs spread?
Continuous runs under a wall. Spread is a pad under a post. Same rectangle math.
Round pier instead?
Use the sonotube or column calculator.
Footer vs footing?
Same pour in most US residential talk — use this page for either search.