Concrete Footing Volume Calculator
Enter dimensions in inches for a rectangular footing. The calculator returns concrete volume, bag counts, and optional material cost.
Why a concrete footing calculator matters
Footings transfer the load of your structure safely into the soil. Whether you are building a deck, a small shed, a retaining wall, or a post-frame structure, estimating the concrete volume correctly is one of the easiest ways to avoid delays and overspending.
If you under-order, your pour can be interrupted and create cold joints or weak sections. If you over-order too much, you pay for concrete you do not need. A practical calculator gives you a quick estimate in cubic feet and cubic yards so you can buy bags confidently or place a ready-mix order with fewer surprises.
What this calculator includes
- Total concrete needed for multiple rectangular footings.
- Volume before waste and volume including a waste factor.
- Conversion to cubic feet, cubic yards, and cubic meters.
- Estimated number of 60 lb and 80 lb premix bags.
- Optional cost estimate when a per-yard price is provided.
Formula used for footing volume
Rectangular footing formula
For each footing:
Volume (ft³) = Length (ft) × Width (ft) × Depth (ft)
Since most plans are marked in inches for smaller jobs, this tool converts inches to feet first:
- Length (ft) = Length (in) ÷ 12
- Width (ft) = Width (in) ÷ 12
- Depth (ft) = Depth (in) ÷ 12
Then:
- Total ft³ = Volume per footing × Number of footings
- Total yd³ = Total ft³ ÷ 27
- Total with waste = Total yd³ × (1 + Waste% ÷ 100)
How to use the calculator
- Enter the number of footings.
- Enter length, width, and depth for each footing in inches.
- Add a waste percentage (8% to 12% is common for many jobs).
- Optionally enter your concrete supplier's price per cubic yard.
- Click Calculate Footing Concrete.
You will get an estimate that can be used for both bagged concrete planning and ready-mix ordering.
Bagged concrete vs ready-mix: quick guidance
When bagged concrete makes sense
- Very small jobs or single-footing repairs.
- Limited site access where a truck cannot reach.
- Projects where labor time is not a major cost factor.
When ready-mix is usually better
- Multiple footings poured the same day.
- Total volume approaching or exceeding about 1 cubic yard.
- Need for consistent mix quality and faster placement.
Common mistakes to avoid
- Ignoring waste: Spillage, uneven subgrade, and form imperfections add up.
- Wrong units: Mixing inches and feet can create major ordering errors.
- No soil verification: Size and depth should follow local code and site conditions.
- No reinforcement plan: Rebar and bar placement should follow structural requirements.
- Poor weather timing: Extreme heat or freezing temperatures change placement and curing practices.
Field checklist before you pour
- Footing layout dimensions checked against plan.
- Excavation bottoms cleaned and level.
- Forms braced and measured for square and elevation.
- Rebar in place with proper cover and ties.
- Anchor bolts, post bases, or dowels ready.
- Curing plan prepared (water cure, curing compound, or cover).
Important note
This calculator is for estimating concrete quantity and cost only. It does not design structural footings. Always follow local building codes, geotechnical recommendations, and engineered drawings where required.