Concrete Footing Calculator
Calculate concrete footing calculator for foundation. Precise material estimations for building contractors and DIY home builders across USA/UK/Canada.
Calculate Concrete Footing Calculator
Enter project dimensions below to compute required material quantities.
Calculation Results
Calculated using verified construction formula: Cubic Yards = (Length * (Width / 12) * (Depth / 12)) / 27 * (1 + Waste %)
Quick Summary
The Concrete Footing Calculator computes concrete volume in cubic yards, cubic feet, 80lb/60lb bags, total weight, and cost estimates for continuous wall footings, deck post piers, and trench foundations.
- Cubic Yards (yd³): Total volume required for continuous trench poured foundations.
- Bagged Mix Options: Bag counts for small deck post footings or pier pours.
- Trench Unevenness Allowance: Includes adjustable safety waste margins.
How to Use the Concrete Footing Calculator
- Enter total Footing Length in feet.
- Enter Footing Width in inches (e.g. 16 inches or 24 inches).
- Enter Footing Depth / Thickness in inches (e.g. 8 inches or 12 inches).
- Adjust the Waste Margin (%) (10% standard for soil trenches).
- Click Calculate to view cubic yards, bag counts, and material costs.
Concrete Footing Calculator Formula & Method
This tool utilizes verified construction geometric formulas to compute material requirements:
Cubic Yards (yd³) = (Volume (cu ft) / 27) * (1 + Waste Margin % / 100)
Where:
- Footing Length: Perimeter or total run length of trench.
- Width & Depth: Cross-sectional measurements of footing trench.
- Waste Factor: Extra volume for unformed earthen trench walls.
Worked Example
Example: 120 Linear Feet Footing (16 Inches Wide by 8 Inches Deep) with 10% Waste
- Linear Length: 120 ft
- Width in Feet: 16 in / 12 = 1.333 ft
- Depth in Feet: 8 in / 12 = 0.667 ft
- Base Volume: 120 * 1.333 * 0.667 = 106.67 cu ft
- Base Cubic Yards: 106.67 / 27 = 3.95 cu yds
Applying the formula yields:
With 10% Waste Margin: 3.95 * 1.10 = 4.35 Cubic Yards
Pre-Mix 80lb Bags Needed: 117.33 / 0.60 = 196 Bags
What This Calculator Includes vs. Does Not Include
What This Calculator Includes
- Continuous Foundation Trench Scoping: Measures volumetric concrete for perimeter footings.
- Pre-Mix Bag vs Ready-Mix Delivery Comparison: Computes batch truck volume and bag equivalents.
What This Calculator Does Not Include
- Foundation Excavation Labor: Backhoe or manual trenching costs.
Tips & Best Practices
- Pour Footings Below Local Frost Line: Footings must extend below the frost depth line to prevent frost heave from cracking your building foundation.
- Use Formwork for Soft Earthen Soil: Earthen trench walls collapse during pouring; wooden forms or Sonotubes keep footing dimensions true.
Common Mistakes to Avoid
- Omitting Steel Rebar Reinforcement: Continuous footings require horizontal steel rebar (minimum #4 or #5 rebar) to resist soil movement and settling.
Frequently Asked Questions (FAQ)
How many cubic yards of concrete do I need for a footing?
Multiply total footing length (ft) by width (ft) by depth (ft) and divide by 27. Add 10% for trench waste.
How wide and deep should a house foundation footing be?
Standard residential wall footings are usually 16 to 24 inches wide and 8 to 12 inches deep, depending on soil load capacity.
How deep must footings be poured for frost protection?
Frost depth ranges from 12 inches in warm southern states to 48+ inches in northern climate zones.
How many 80lb bags of concrete for a deck post footing?
A standard 12-inch diameter by 36-inch deep deck post pier requires about 4 to 5 bags of 80lb concrete.
Should footings be poured directly on soil?
Footings should be poured on undisturbed, compacted virgin soil or crushed gravel base, never on loose backfill.
How long must footings cure before laying concrete blocks?
Concrete footings should cure for at least 24 to 48 hours before laying foundation stem walls or blocks.
How much concrete waste should be added for unformed trench footings?
Add 10% to 15% waste margin for earthen trenches due to irregular soil walls.
What strength concrete mix is required for footings?
Building codes typically specify 3,000 PSI to 4,000 PSI compressive strength concrete for footings.
Is this concrete footing calculator free to use?
Yes, TibCal's Concrete Footing Calculator is 100% free.