Concrete Footing Calculator Guide - Yards, Bags, and 2026 Cost
Estimate concrete for continuous footings by run length, width, depth, waste factor, cubic yards, bag count, ready-mix cost, rebar, inspection, access, and quote checks.
A concrete footing estimate starts with the footing shape. For a continuous footing, calculate the volume from run length, width, and depth, then add waste before comparing bags or ready-mix.
Suggested citation: a 40 ft continuous concrete footing that is 16 in wide and 8 in deep needs about 1.45 yd3 with 10% waste, or roughly 66 80 lb bags before any extra jobsite cushion.
Use the Concrete Footing Calculator when you already know the planned footing dimensions. It estimates cubic yards, cubic feet, bag count, waste factor, and material-only cost for wall, garage, shed, and deck beam footings. If the contractor quote is written by linear foot, use the Concrete Footing Cost per Linear Foot Guide to separate ready-mix material from excavation, rebar, inspection, access, and labor scope.
For worked numbers, see Concrete Footing Calculation Examples. If the search question is about choosing or checking footing dimensions, read the Footing Size Calculator Guide before treating the volume result as a design decision. If the open issue is vertical depth, frost line, excavation depth, or inspection scope, use the Footing Depth Calculator Guide. If the project uses round pier holes, use the Concrete Post Hole Calculator instead.
Quick answer
For a continuous footing, multiply the run length by footing width by footing depth, convert the result to cubic yards, then add waste. A 40 ft footing that is 16 in wide and 8 in deep needs about 1.32 yd3 before waste, or 1.45 yd3 with a 10% waste factor.
That number is a material planning estimate, not footing design approval. A real footing project can also include excavation, trench cleanup, forms, rebar, chairs, dowels, inspection, pump or buggy service, access, weather delays, cleanup, permits, tax, and labor. Confirm width, depth, reinforcement, frost depth, and local code before ordering concrete.
Footing volume formula
For a continuous footing measured in feet:
cubic feet = length ft x width ft x depth ft
cubic yards = cubic feet / 27
If width and depth are measured in inches:
cubic yards = length ft x width in x depth in / 144 / 27
Then add waste:
order quantity = cubic yards x (1 + waste percentage)
If the project has multiple identical runs, multiply by the number of runs. If the runs have different sizes, calculate each group separately and add the totals before pricing.
If a footing includes a thickened pad, step, grade beam, or a separate slab, estimate each section separately. That keeps the order quantity and contractor quote easier to review.
For round pier holes or fence posts, use the Concrete Post Hole Calculator instead of the continuous footing workflow.
Common footing size examples
These examples use 10% waste. They are material planning numbers, not structural specifications.
| Footing run | Size | Base volume | With 10% waste |
|---|---|---|---|
| 20 ft | 12 in x 8 in | 0.49 yd3 | 0.54 yd3 |
| 40 ft | 16 in x 8 in | 1.32 yd3 | 1.45 yd3 |
| 60 ft | 18 in x 10 in | 2.78 yd3 | 3.06 yd3 |
| 84 ft | 18 in x 10 in | 3.89 yd3 | 4.28 yd3 |
| 100 ft | 24 in x 12 in | 7.41 yd3 | 8.15 yd3 |
Bag and delivery checks for the same examples:
- 20 ft at 12 in x 8 in: about 25 80 lb bags, or about $214.10 at $165/yd3 plus a $125 delivery fee.
- 40 ft at 16 in x 8 in: about 66 80 lb bags, or about $364.25 delivered.
- 60 ft at 18 in x 10 in: about 138 80 lb bags, or about $629.90 delivered.
- 84 ft at 18 in x 10 in: about 193 80 lb bags, or about $831.20 delivered.
- 100 ft at 24 in x 12 in: about 367 80 lb bags, or about $1,469.75 delivered.
The bag counts use a common 0.60 ft3 yield for 80 lb bags. Use the yield printed on the bag you plan to buy.
Common footing project scenarios
The same formula works for many continuous footings, but the estimating risk is different by project type.
| Project | Common estimating issue | Calculator note |
|---|---|---|
| Short garden wall or small retaining edge | Often simple geometry, but trench shape can be rough. | Measure actual width and depth after excavation. |
| Shed or small outbuilding footing | May need anchor hardware, frost depth, or a slab connection. | Keep footing concrete separate from slab concrete. |
| Garage perimeter footing | Multiple runs, corners, rebar, and inspection timing matter. | Use total run length or calculate each side separately. |
| Addition or foundation footing | Code, soil, frost, and design requirements are central. | Use calculator only after approved dimensions are known. |
| Deck beam footing | Some designs use continuous footings, others use round piers. | Do not mix pier holes into continuous footing volume. |
If the project uses round holes, use the Concrete Post Hole Calculator or the Concrete Volume Calculator if you need a more general shape workflow. If the footing is paired with a slab, estimate the slab separately with the Concrete Slab Calculator.
Choose the right footing calculator setup
The right setup depends on the footing shape, not just the project name. Before pricing concrete, match the work to the correct volume method.
| Footing type | Use this setup | Common mistake |
|---|---|---|
| Continuous strip footing | Total run length x width x depth | Using slab square footage instead of run length. |
| Multiple footing runs | Calculate each run group, then add totals | Averaging different widths and hiding heavy sections. |
| Rectangular pad footing | Length x width x depth for each pad | Treating isolated pads as one continuous run. |
| Round pier or post footing | Cylinder volume by diameter and depth | Using a continuous footing calculator for round holes. |
| Footing plus slab | Estimate footing and slab separately | Combining both into one thickness and losing audit detail. |
This matters for quotes. A contractor bid that includes footings, stem walls, and a slab can look expensive next to a concrete-only footing calculation even when the bid is reasonable. Keep each concrete section visible so the scope is easy to compare.
2026 footing cost sanity check
Footing cost pages often discuss installed pricing by linear foot or by the broader foundation project. That can help you screen a bid, but it is not the same as concrete material cost. Installed footing work may include excavation, trench cleanup, forms, rebar, dowels, inspection timing, pump or buggy service, weather delays, permits, cleanup, overhead, and labor.
Use two separate checks:
installed quote per linear ft = contractor quote / total footing run
ready-mix material = cubic yards after waste x price per yard + delivery fees
For example, a $2,400 installed quote for a 40 ft footing is $60.00 per linear ft. A $5,000 installed quote for an 84 ft garage perimeter footing is about $59.52 per linear ft. Compare that installed number with the ready-mix material line before assuming the concrete itself is expensive.
Then compare the written scope:
| Footing scope | Why the quote can move |
|---|---|
| Shallow non-structural footing | Usually simpler, but still needs correct dimensions and base conditions. |
| Code-inspected foundation footing | Inspection timing, rebar placement, frost depth, and permit coordination matter. |
| Over-dug or soft trench | Extra concrete, cleanup, soil correction, or forms may be needed. |
| Garage or addition footing | Access, layout, dowels, stem walls, and slab coordination can change scope. |
| Pump or buggy placement | Poor chute reach can add equipment and labor. |
| Water or cave-in risk | Wet trenches and loose soil can change volume and schedule. |
If a quote looks high compared with the ready-mix material line, ask which of these scope items are included. If a quote is unusually low, confirm footing size, excavation, rebar, inspection responsibility, permit handling, access, cleanup, and what happens if the trench is larger than planned.
Field measurement check after excavation
A footing estimate should be checked again after the trench is dug. Planned dimensions are useful for budgeting, but the concrete truck sees the actual hole in the ground.
Use this field checklist before confirming the order:
| Field check | Why it matters |
|---|---|
| Actual trench width | Loose sides, shovel cleanup, or over-digging increase volume. |
| Actual trench depth | Low spots and uneven bottoms add concrete. |
| Number of runs | Missing short returns or interior runs can understate the order. |
| Wet or soft spots | Soil correction, cleanup, or forms may be needed before pour. |
| Rebar clearance | Chairs, dowels, and bar spacing must fit before concrete arrives. |
| Inspection status | Some footings cannot be poured until inspection is complete. |
If the trench is wider or deeper than planned, recalculate with actual dimensions. A small increase across a long footing run can add meaningful cubic yards.
Order sequence after excavation and inspection
For permitted or structural footing work, the safest order is not "calculate, then immediately order." Use this sequence so the concrete quantity and delivery timing match the actual site.
- Confirm approved footing dimensions, reinforcement, and inspection requirements.
- Excavate and clean the trench or forms.
- Measure actual width, depth, and run length after excavation.
- Place rebar, chairs, dowels, and required hardware.
- Pass required inspection before scheduling the pour if the project is inspected.
- Recalculate cubic yards with actual dimensions and waste.
- Confirm ready-mix delivery, chute reach, pump, buggy, or wheelbarrow route.
This sequence prevents two expensive problems: ordering too little concrete because the trench is larger than the plan, or scheduling a truck before the footing is ready to pour.
Example: wall footing
Assume:
- Length: 40 ft
- Width: 16 in
- Depth: 8 in
- Waste: 10%
Base volume:
40 x 16 x 8 / 144 / 27 = 1.32 yd3
With waste:
1.32 x 1.10 = 1.45 yd3
Planning estimate: about 1.45 cubic yards after waste.
At $165 per yd3 and a $125 delivery or short-load fee:
1.45 x $165 = $239.25
$239.25 + $125 = $364.25
This is material and delivery only. It does not include excavation, rebar, forms, inspection, pump service, cleanup, or labor.
Example: garage footing runs
Assume two footing runs, each 24 ft long, 18 in wide, and 10 in deep:
24 x 18 x 10 / 144 / 27 = 1.11 yd3 per run
1.11 x 2 runs = 2.22 yd3
2.22 x 1.10 = 2.44 yd3
Planning estimate: about 2.44 cubic yards after waste.
For garage slabs, calculate the slab separately with the Concrete Garage Slab Calculator.
Example: full garage perimeter footing
If the total footing run around a garage is 84 ft, 18 in wide, and 10 in deep:
84 x 18 x 10 / 144 / 27 = 3.89 yd3
3.89 x 1.10 = 4.28 yd3
At $165 per yd3 and a $125 delivery fee:
4.28 x $165 = $706.20
$706.20 + $125 = $831.20
That order size is usually a ready-mix planning signal. It may also require inspection timing, rebar placement, truck access, chute reach, pump planning, or buggy placement before the concrete arrives.
Example: mixed footing runs
Many projects have more than one footing size. Do not average the sizes if the work includes separate heavy-load sections.
Assume:
- 48 ft of standard footing at 16 in wide and 8 in deep.
- 16 ft of heavier footing at 24 in wide and 12 in deep.
- Waste: 10%.
Standard footing:
48 x 16 x 8 / 144 / 27 = 1.58 yd3
Heavier footing:
16 x 24 x 12 / 144 / 27 = 1.19 yd3
Total with waste:
1.58 + 1.19 = 2.77 yd3
2.77 x 1.10 = 3.05 yd3
This approach makes the quote easier to audit because the heavier sections are visible instead of hidden inside one average footing size.
Footing size and code planning
Footing width and depth are not universal. They depend on building loads, soil bearing capacity, frost depth, slope, seismic or wind conditions, reinforcement, local code, and the approved plan. Use the calculator after the footing size is known. Do not use a material estimate to choose the footing size.
For material planning, measure the trench after excavation. A footing trench that is over-dug, sloped, uneven, or soft-sided can use more concrete than the plan dimension suggests.
Rebar, dowels, and inspection planning
Rebar usually does not change the concrete volume enough for a homeowner-level material estimate, but it can strongly affect schedule, scope, and bid quality.
Before ordering concrete, align these details:
| Detail | Why it matters |
|---|---|
| Rebar size and spacing | Needed for material buying and inspection. |
| Chairs or supports | Keeps steel in position during the pour. |
| Dowels or anchor bolts | Must be placed according to the plan or hardware layout. |
| Inspection window | Concrete delivery should not arrive before approval. |
| Pour sequence | Footings, stem walls, piers, and slabs may be separate orders. |
| Access and placement | Rebar and trench layout can limit chute, buggy, or pump routing. |
Use the calculator to plan concrete quantity. Use the approved plan, local code, or a qualified professional for footing design and reinforcement requirements. For a material takeoff from a known plan, use the Concrete Rebar Calculator Guide to keep bar length, laps, dowels, chairs, and stick count separate from footing concrete volume.
Bags or ready-mix for footings?
Small shed or deck footings may be possible with bags. Continuous wall or garage footings can quickly become a ready-mix job.
For the 1.45 yd3 wall footing example, 80 lb bags at a common 0.60 ft3 yield would be:
1.45 x 27 / 0.60 = 65.25 bags
Round up to at least 66 bags. If the estimate is dozens of bags, compare the bag count with local ready-mix delivery and short-load fees using the Ready-Mix vs Bags Calculator.
For bag yield references, see Concrete Bags per Yard. If you are pricing bagged material, also check How Much Is a Bag of Concrete?.
Bag count pressure table
Footings often move into ready-mix territory faster than small slabs because the volume is concentrated in long runs.
| Rounded 80 lb bag count | Practical planning note |
|---|---|
| Under 30 bags | Bags may be practical for short, non-structural runs. |
| 30 to 70 bags | Compare mixer rental, crew pace, and delivery fees. |
| 70 to 150 bags | Ready-mix should be quoted before buying bags. |
| 150+ bags | Usually a ready-mix, pump, or buggy planning discussion. |
The threshold depends on site access, minimum delivery charges, crew size, and whether the footing needs to be placed continuously after inspection.
Material cost vs project cost
For ready-mix:
ready-mix total = cubic yards after waste x price per yard + delivery fees
Using the 1.45 yd3 example, a $165 per yd3 ready-mix price, and a $125 delivery fee:
1.45 x $165 = $239.25
$239.25 + $125 = $364.25
For bagged concrete:
bagged total = rounded bag count x price per bag
At 66 bags and $5.50 per bag:
66 x $5.50 = $363.00
Those are material-only planning numbers. They do not include excavation, form work, rebar, inspection, pump or buggy service, taxes, labor, cleanup, or contractor overhead.
Use this broader planning formula for footing project conversations:
project total =
concrete material
+ delivery or short-load fees
+ excavation, trench cleanup, forms, and base preparation
+ rebar, chairs, dowels, anchor hardware, and inspections
+ pump or buggy service, cleanup, permits, tax, and labor
| Cost item | Why it matters |
|---|---|
| Excavation accuracy | Over-digging increases concrete volume quickly. |
| Frost depth and code | Footings may need specific depth or inspection before pour. |
| Rebar and dowels | Reinforcement is often separate from concrete material cost. |
| Formwork | Some footings are poured in trenches; others need forms. |
| Access | Chute reach, pump, buggy, or wheelbarrow placement changes labor. |
| Inspection timing | A missed inspection can delay the pour. |
| Weather and water | Wet trenches, loose soil, and cave-ins can change volume and schedule. |
For a broader material-only pricing workflow, see Concrete Cost per Yard. For a bagged vs delivered buying decision, see Ready-Mix vs Bags Cost.
Ready-mix quote checklist
If you order concrete directly for footings, collect these details from each supplier:
- Cubic yards after waste and whether the supplier rounds the order.
- Price per yd3, delivery, short-load fee, fuel surcharge, environmental fee, tax, and waiting time.
- Mix strength, air entrainment if needed, additives, and slump target.
- Truck access, chute reach, pump, buggy, or wheelbarrow placement.
- Minimum load, cancellation window, weather policy, and delivery time window.
- Whether the supplier only delivers concrete or provides any placement help.
Then match the supplier quote against the contractor bid. If they are far apart, ask whether the contractor included over-dig waste, pump/buggy service, waiting time, rebar coordination, inspection timing, or cleanup.
Low-bid red flags
A low footing bid may be a good deal, or it may be missing expensive scope. Ask follow-up questions when you see these signs:
| Red flag | What to ask |
|---|---|
| Only lists "footing concrete" | Are excavation, forms, rebar, and inspection included? |
| No footing dimensions | What run length, width, depth, and number of sections are priced? |
| No rebar detail | What bar size, spacing, chairs, dowels, and overlaps are included? |
| No placement method | Can the truck reach the trench, or is pump/buggy/wheelbarrow labor included? |
| No over-dig policy | Who pays if the trench is wider, deeper, wet, or caved in? |
| No permit/inspection note | Who schedules inspection and owns delay risk? |
The best footing quote names the dimensions, reinforcement, inspection responsibility, access method, exclusions, and cleanup clearly enough that you can compare it with another bid.
Footing planning checklist
- Confirm footing width, depth, reinforcement, frost depth, and code requirements before estimating material.
- Measure trench depth and width after excavation.
- Add waste for uneven trench sides, loose soil, and over-excavation.
- Calculate separate footing groups separately if sizes differ.
- Ask ready-mix suppliers about minimum loads and short-load fees.
- Do not use a material calculator as structural design approval.
- Confirm inspection timing before the pour if the footing is permitted.
- Confirm truck access, chute reach, pump needs, buggy route, or wheelbarrow distance.
- Keep the material-only estimate separate from installed project cost.
Quote checklist for contractors
Before accepting a footing bid, ask what is included in writing:
- Total run length, footing width, depth, and number of footing sections.
- Soil preparation, excavation, trench cleanup, and formwork.
- Concrete mix, strength, slump, air entrainment if needed, and additives.
- Rebar size, spacing, chairs, dowels, anchor bolts, or embedded hardware.
- Frost-depth, local code, inspection, and permit responsibilities.
- Whether slabs, stem walls, piers, or pads are included separately.
- Truck access, chute reach, pump, buggy, or wheelbarrow placement.
- Spoil removal, cleanup, weather delay policy, warranty, and payment schedule.
That checklist helps turn the calculator result into a quote-comparison tool.
Bid comparison table
Use this table when footing bids are difficult to compare:
| Quote item | Bid A | Bid B | Why it matters |
|---|---|---|---|
| Total run length | Confirms both bids measure the same footing work. | ||
| Width and depth | Small dimension changes can move cubic yards quickly. | ||
| Excavation/trench cleanup | Over-dig, cave-ins, and cleanup affect volume and labor. | ||
| Rebar/dowels | Reinforcement can be a major non-concrete cost. | ||
| Inspection/permit handling | Missed inspections can delay the pour. | ||
| Placement method | Chute, pump, buggy, or wheelbarrow changes cost. | ||
| Exclusions | Clarifies whether slabs, piers, stem walls, and cleanup are separate. |
The clearest bid is usually more useful than the shortest bid. For footing work, the dimensions, excavation, rebar, inspection, placement method, cleanup, and exclusions should be written clearly enough to compare.
Common estimating mistakes
- Using a slab calculator for continuous footings.
- Forgetting to convert footing width and depth from inches.
- Measuring plan dimensions but ignoring over-excavated trenches.
- Combining different footing sizes into one rough average.
- Forgetting waste for uneven soil, cave-ins, or loose trench sides.
- Treating material-only cost as the installed footing cost.
- Buying dozens of bags before comparing ready-mix delivery.
- Treating a material estimate as structural or code approval.
FAQ
What calculator should I use for continuous footings?
Use the Concrete Footing Calculator. It is built for footing run length, width, depth, number of runs, waste factor, bag count, and material cost.
How much waste should I add for footings?
A 10% waste factor is a practical planning default, but uneven excavation, loose soil, wet conditions, or over-digging can require more.
Can I use a slab calculator for footings?
Not usually. Footings are calculated from run length, width, and depth, while slabs are calculated from length, width, and thickness across an area.
Does this decide footing size?
No. It estimates material quantity only. Footing size depends on loads, soil, frost depth, reinforcement, local code, and project design.
How many yards for a 40 ft footing?
A 40 ft continuous footing that is 16 in wide and 8 in deep is about 1.32 yd3 before waste. With 10% waste, plan around 1.45 yd3 before pricing or ordering.
How many 80 lb bags for a 40 ft footing?
At 16 in wide, 8 in deep, and 10% waste, a 40 ft footing is about 1.45 yd3. With 80 lb bags at a common 0.60 ft3 yield, that is about 66 bags after rounding up.
Should footing concrete be ordered by yards or bags?
Use cubic yards first because that is the shared volume unit. After the yardage is known, compare ready-mix delivery with bag count, bag price, and labor.
Does the estimate include rebar or excavation?
No. The calculator estimates concrete material quantity and material-only cost. Rebar, excavation, forms, inspections, pump service, cleanup, permits, and labor are separate.
Should I measure before or after excavation?
Use plan dimensions for early budgeting, then recheck after excavation. If the actual trench is wider, deeper, uneven, wet, or caved in, recalculate before confirming the concrete order.
Can I average different footing sizes?
Avoid averaging if the project has distinct footing groups. Calculate each run or group separately, then add the totals before applying waste. This makes quotes easier to audit.
Does rebar reduce the concrete quantity?
For most planning estimates, rebar displacement is ignored because trench variation and waste are usually larger. Rebar still matters for inspection, placement timing, and contractor scope.
Why is a footing quote higher than the concrete material estimate?
Footing material cost usually covers ready-mix and sometimes delivery only. A contractor quote may include excavation, trench cleanup, rebar, chairs, dowels, forms, inspections, permits, pump or buggy service, cleanup, overhead, and labor.
What should I check before accepting a low footing bid?
Confirm the footing run length, width, depth, frost-depth assumptions, rebar, dowels, inspection responsibility, permit handling, placement method, cleanup, weather policy, exclusions, and warranty. A low footing bid can be missing scope that is expensive to fix later.
Should I order footing concrete before inspection?
For inspected work, do not schedule delivery until the required pre-pour inspection is handled or clearly coordinated. A truck that arrives before rebar, forms, and inspection are ready can create delay fees or a missed pour window.
How do I estimate footings with a slab?
Estimate the footing volume separately from the slab volume, then add the orders only after each section has its own waste factor and cost check. This makes bids easier to audit and avoids hiding thickened edges or footing runs inside a simple slab number.
Next step
Enter your run length, width, depth, number of runs, and waste factor in the Concrete Footing Calculator. Then compare the material total in the Concrete Cost Calculator. If the footing is part of a slab project, estimate the slab separately with the Concrete Slab Calculator. For written pricing context, read Concrete Cost per Yard and Ready-Mix vs Bags Cost. For cost-specific line items, use the Footing Cost Calculator Guide. If the search or bid uses the word footer, use the Concrete Footer Calculator Guide.
Quote planning next step
Turn this guide into a concrete buying check
Run the matching calculator, then compare ready-mix, bagged concrete, delivery fees, access needs, and quote gaps before you buy materials or approve a contractor number.