Concrete Footing Calculator
Calculate concrete volume in cubic yards and determine 80lb and 60lb premix bag counts for cylindrical Sonotubes and square post piers.
Recommended Tools & Equipment
Tested hardware and components for high reliability
How to Calculate Footing Concrete Volume
Post footings and piers transfer the weight of decks, porches, and buildings directly into the load-bearing soil below the winter frost line to prevent frost heave.
Cylinder (Sonotube) Volume
V = π × (Diameter / 2)² × Depth
Premix Bag Yields
80 lb bag = 0.60 cu ft (45 bags / cu yd)
60 lb bag = 0.45 cu ft (60 bags / cu yd)
Frost Depth Requirements
Local building codes dictate the minimum footing depth required to reach below the maximum frost penetration line. In northern states, this is often 42 to 48 inches; in southern regions, 12 to 24 inches may be sufficient.
Frequently Asked Questions
When is it cheaper to order a concrete mixer truck vs. bags?
If your project requires more than 1.5 to 2.0 cubic yards (approx. 70 to 90 eighty-pound bags), ready-mix truck delivery is typically more economical and saves dozens of hours of manual mixing labor.
What does a bell footing base do?
Flaring out the bottom of the pier hole into an inverted bell shape triples the bearing surface area against the soil and physically anchors the pier against frost uplift.
How much water do I add to an 80lb bag of concrete?
Most standard 80lb bags require approximately 3 quarts (2.8 liters) of clean water. Too much water dilutes the cement paste and dramatically reduces cured compressive PSI strength.