Pick the tube diameter, enter pier depth and count — yards and per-pier bag counts solve live.
Standard Sonotube sizes.
Below frost line + above grade.
Labor (optional)
Order quantity
0.77
CU YDS
Bill of materials+10% waste
Ready-mix concrete
3.14 cu ft per pier
Net 0.7 cu yd · Waste +0.07 cu yd
80-lb bags (alt.)
≈ 5.8 bags per pier
Net 31 bags · Waste +10%
60-lb bags (alt.)
Net 42 bags · Waste +10%
Cost projection
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Order quantity
0.77 cu yd
Pier volume is π × r² × depth ÷ 27 — a 12 in diameter, 4 ft deep pier is π × 0.25 × 4 ÷ 27 ≈ 0.12 cubic yards.
Pick the tube diameter, enter pier depth and count — yards and per-pier bag counts solve live.
Sonotubes come in even-inch diameters (8, 10, 12, 18); size the tube to the post base plus bearing requirements.
Set piers below the frost line and bell the bottom in soft soils for extra bearing area.
One 80-lb bag yields about 0.6 cu ft — a 12 in × 4 ft pier needs roughly 5–6 bags.
V = π r² h ÷ 27
A 12 in diameter, 4 ft deep pier is about 0.12 cubic yards — roughly 5–6 eighty-pound bags (45 bags per yard at 0.6 cu ft per bag).
Volume = π × r² × depth ÷ 27. A 12 in × 4 ft pier is π × 0.25 × 4 ÷ 27 ≈ 0.12 cubic yards.
Below the local frost line — typically 36–48 in in cold climates — plus about 6 in above grade.
Sonotubes come in even-inch diameters (8, 10, 12, 18). Size the tube to the post base plus bearing requirements, and bell the bottom in soft soils for extra bearing area.
Yes for structural posts — one or two vertical bars tied to the post base keeps the pier from splitting under load.
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