Formula or decision rule
footing length × width × depth × number of footings × allowance factor ÷ bag yield- Measure each footing group separately if dimensions differ.
- Depth in the volume formula is the concrete depth, not total excavation depth.
- Use the local approved design before entering dimensions.
Footing calculation boundaries
| Value | Source | Calculator action |
|---|---|---|
| Dimensions | approved project plan | multiply |
| Footing count | site layout | multiply |
| Bag yield | QUIKRETE No. 1101 sheet | divide |
| Purchase bags | calculated quotient | round up |
Work through the project
Use approved dimensions
Enter dimensions from the plan or authority responsible for the work, not a generic online rule of thumb.
Group like footings
Calculate each distinct size as its own rectangular group, then add whole-bag needs only after reviewing the pours.
Verify access and batch plan
A correct volume does not establish that hand mixing is suitable for the placement size or timing.
Safety and scope
- Call the applicable utility-location service before excavation.
- Do not use this material estimate as structural or code approval.
Sources and scope
Source links reviewed July 16, 2026. A review date is not the document's publication date.
- QUIKRETE: Concrete Mix No. 1101 Technical Data SheetNorth America · manufacturer data sheet
Bag counts are based on stated approximate yield and must be rounded up to whole bags.
- National Institute of Standards and Technology: NIST Guide to the SI, Appendix B — Conversion FactorsUnited States · government standard
Code retains exact defining constants where NIST identifies an exact relationship.