Construction • Material Estimator

Concrete Footing & Pier Calculator

Calculate concrete volume, premix bags, sonotube cardboard forms, and rebar for deck piers, strip trench footings, and column spread pads

Waste Buffer:

Sonotube Pier Dimensions

piers
in
Must reach below local frost line (36"–48")
in
Keeps wooden posts off moist soil
in

Material Costs

Total Footing Concrete
1.63 cu yd
44.09 Cubic Feet • 1.25 m³ (incl. 10% waste buffer)
$550 Est.
6.68 cu ft / pier
Premix Bags (80 lb)
74 bags
Or 98 bags of 60 lb premix
Sonotube 4-ft Forms
12 tubes
Cardboard cylinder tube forms
Steel Reinforcement Rebar
13 bars (10ft #4)
13 vertical dowels + 0 continuous
Frost Depth Standard
48" penetration
Prevents seasonal frost heave
Sonotube Pier Cross-Section12" Tube × 48" Depth
Ground Line 12" Sonotube Pier 24" Bell Base (Bigfoot) Frost Line

Deck Footing & Frost Depth Guidelines

What is Frost Heave?

When moisture in soil freezes during winter, it expands by 9% and pushes upward with immense hydraulic force (frost heave). If deck piers or footings are poured above the local frost line, the entire deck or structure will heave unevenly and crack. Always dig 6" below your municipal frost line depth.

Why Use a Flared Bell Base (Bigfoot)?

Flared bell footing pads provide two critical structural benefits: (1) They dramatically increase the bearing footprint to distribute heavy loads without soil settling; (2) The bell shape acts as an anchor that prevents frozen soil from gripping the sides of the tube and lifting the pier upward.

Frequently Asked Questions (FAQ)

A 12-inch diameter cylindrical pier 48 inches deep contains 3.14 cubic feet (0.12 cubic yards) of concrete. If using pre-mixed concrete bags, this requires approximately 5.5 bags (80 lb) or 7.5 bags (60 lb) per pier including standard compaction loss.

Deck footings must extend at least 6 inches below the local frost depth line to prevent seasonal frost heave. Depending on your region, frost depths range from 12 inches in southern warm climates to 36–48+ inches across northern US and Canadian regions. Always check with your local municipal building department for code requirements.

A flared bell base (such as a Bigfoot pier footing form) doubles the bearing footprint on native subsoil, spreading structural loads evenly. Crucially, the bell flange acts as an underground mechanical anchor that prevents frozen soil from gripping the sides of the cardboard tube and lifting the column upward.

Most residential deck codes recommend a minimum of two to four vertical #4 (1/2-inch) rebar rods running the full length of the pier with 3 inches of clear concrete coverage from soil. Adding horizontal wire hoops every 12 inches provides additional lateral and seismic load resistance.

While concrete achieves roughly 70% of its rated compressive strength within 7 days, you can typically set post anchor brackets and begin light timber framing after 24 to 48 hours in warm, dry weather. Avoid placing full structural loads or heavy equipment on the footings until 7 days of curing have elapsed.