Concrete Footings Calculator
Estimate how much concrete you need for common footing types. Enter dimensions in feet.
How to use this footings concrete calculator
Footings transfer structural loads into the ground, so getting the concrete volume right matters for both budget and scheduling. This calculator helps you quickly estimate concrete needs for three common footing geometries: rectangular pad footings, continuous strip footings, and circular pier footings.
- Choose the footing type that best matches your project.
- Enter dimensions in feet and the total number of similar footings.
- Add a waste factor (usually 5% to 15%).
- Review output in cubic feet, cubic yards, and cubic meters.
Concrete footing volume formulas
1) Rectangular pad footing
For square or rectangular pads, the volume of one footing is: Length × Width × Depth. Multiply by the number of footings for total volume.
2) Continuous strip footing
For perimeter or wall strip footings: Run Length × Width × Depth, then multiply by the number of identical strips. If strips are different lengths, calculate each separately and add the totals.
3) Circular pier footing
For cylindrical piers, use: π × (Diameter ÷ 2)2 × Depth, then multiply by quantity.
Why convert to cubic yards?
Ready-mix suppliers typically quote and deliver concrete in cubic yards. On-site bag mixes are practical for very small jobs, but once you approach about one cubic yard, ordering ready-mix often saves time and labor.
Example: quick footing estimate
Suppose you need 8 rectangular pad footings, each 2.5 ft × 2.5 ft × 1 ft:
- One footing volume: 2.5 × 2.5 × 1 = 6.25 cubic feet
- 8 footings total: 6.25 × 8 = 50 cubic feet
- Add 10% overage: 50 × 1.10 = 55 cubic feet
- Convert to yards: 55 ÷ 27 ≈ 2.04 cubic yards
In this case, you would likely order around 2.1 cubic yards (confirm with your supplier's minimum increments).
Practical tips before ordering
- Confirm design dimensions: Follow stamped plans and local building code requirements.
- Check excavation conditions: Irregular trenches and loose soil can increase actual usage.
- Account for grade variation: Sloped sites can change effective footing depth.
- Include waste: Spillage, over-excavation, and form leakage are common.
- Coordinate pour logistics: Access, weather, and crew availability affect productivity.
Frequently asked questions
How much waste should I add?
For clean forms and straightforward layouts, 5% may be enough. For complex layouts, uneven excavation, or remote placements, 10% to 15% is often safer.
Should I use bags or ready-mix?
Small spot repairs can use bagged concrete. For larger footing projects, ready-mix typically provides better consistency and faster placement.
Do I need to include rebar volume in the calculation?
Rebar displaces a small amount of concrete, but in most residential estimates the difference is minor. Most builders do not subtract it from quantity calculations.