Concrete Footing Calculator
Use this footing calculator concrete tool to estimate cubic yards, cubic feet, and bagged concrete for rectangular footings.
Tip: For ready-mix delivery, contractors often round up to the nearest 0.25 cubic yard.
How to use this footing calculator concrete tool
This concrete footing calculator is built for quick planning when you are pouring pad footings, deck footings, shed footings, or light foundation supports. Enter the count of footings and the dimensions of one footing, then the calculator multiplies the total volume and shows recommended order quantity with waste.
- Length and width are in feet.
- Depth is in inches, since footing thickness is often called out that way on plans.
- Waste factor helps cover spillage, uneven subgrade, and minor over-excavation.
- Price per yard gives a quick material cost estimate.
Formula used for concrete footing volume
The calculator uses standard volume math:
- Depth in feet = depth in inches ÷ 12
- Volume of one footing (ft³) = length × width × depth(ft)
- Total volume (ft³) = one footing volume × quantity
- Total volume (yd³) = total ft³ ÷ 27
- Waste-adjusted volume = yd³ × (1 + waste%)
It also estimates equivalent bag counts for small jobs:
- 80 lb bag ≈ 0.60 ft³
- 60 lb bag ≈ 0.45 ft³
- 50 lb bag ≈ 0.375 ft³
Worked example
Suppose you are installing 6 footings, each measuring 2 ft × 2 ft × 12 in.
- Depth = 12 ÷ 12 = 1 ft
- One footing volume = 2 × 2 × 1 = 4 ft³
- Total volume = 4 × 6 = 24 ft³
- Cubic yards = 24 ÷ 27 = 0.89 yd³
- At 10% waste = 0.98 yd³ (round up for ordering)
In practice, you would likely order about 1.00 yd³ depending on site conditions and supplier minimums.
Typical footing sizes and approximate concrete volume
| Footing Size (L × W × D) | Volume per Footing (ft³) | Volume per Footing (yd³) |
|---|---|---|
| 2' × 2' × 10" | 3.33 | 0.12 |
| 2' × 2' × 12" | 4.00 | 0.15 |
| 2.5' × 2.5' × 12" | 6.25 | 0.23 |
| 3' × 3' × 12" | 9.00 | 0.33 |
| 4' × 4' × 12" | 16.00 | 0.59 |
When to increase waste factor
A 5% to 10% waste factor is common for clean, controlled placements. Consider using 12% to 15% if your site has difficult access, rough excavation, or if forms are inconsistent. It is usually cheaper to have a little extra than to come up short in the middle of a pour.
Important field considerations
1) Soil bearing and local building code
Footing size is not only about concrete volume. It must satisfy structural loads and local bearing requirements. Always verify dimensions against approved plans and code requirements.
2) Rebar and reinforcement
Many footings require reinforcement steel. Rebar does not significantly change gross concrete volume for small projects, but spacing, cover, and placement quality are critical for performance.
3) Frost depth and excavation shape
In cold climates, bottom of footing often needs to be below frost depth. If holes are belled or overcut, your real concrete usage may be higher than plan dimensions.
Ready-mix vs bagged concrete
- Bagged concrete is good for very small jobs and remote areas.
- Ready-mix is usually more consistent and efficient for larger volume pours.
- Check delivery minimums and short-load fees before ordering.
Quick checklist before you order
- Confirm final footing dimensions from plan.
- Measure actual excavation depth and squareness.
- Set forms and verify elevations.
- Add proper waste percentage in the calculator.
- Round order quantity up to practical delivery increments.
FAQ: footing calculator concrete
Can I use this for continuous strip footings?
Yes. Enter quantity as 1, then use total run length as “length,” strip width as “width,” and footing thickness as “depth.”
Why does calculator output differ from my supplier quote?
Suppliers may include delivery constraints, truck minimums, and practical rounding rules. Use this tool for planning and budgeting, then confirm with your supplier.
How accurate is the cost estimate?
It is a quick estimate only. Final price may vary based on strength mix, additives, travel time, and market conditions.
Final note
A reliable footing calculator concrete estimate saves time, prevents under-ordering, and helps avoid expensive delays. Use this tool early in planning, then verify structural dimensions and code requirements before construction.