Sonotube Calculator: Concrete for Tubes and Piers

Concrete per foot of Sonotube is π × r²: a 12 in tube holds 0.79 cu ft per foot (Sonoco's chart: 0.80), so a 4 ft tube takes 3.1 cu ft, or 6 bags of 80 lb Quikrete Concrete Mix. Four of them take 21 bags.

Set up for: deck footings or sonotubes · Different project?

Footing size and depth come from your plan or local building department, not from us.

Sonotube sizes and concrete per foot

Diameter	Cu ft per ft (π r²)	Builder's Tube chart	Sonoco brochure, cu yd per 12 ft
6 in	0.20	0.20	0.088
8 in	0.35	0.35	0.155
10 in	0.55	0.55	0.242
12 in	0.79	0.80	0.349
14 in	1.07	—	0.475
16 in	1.40	—	0.62
18 in	1.77	—	0.785
20 in		—	0.97
22 in		—	1.173
24 in	3.14	—	1.397
26 in		—	1.639
28 in		—	1.901
30 in		—	2.182
32 in		—	2.483
34 in		—	2.802
36 in		—	3.142

Sonoco's charts: “Cubic feet of concrete per foot of height” (Builder's Tube) and “Concrete requirements (Expressed in cubic yards for columns of various heights)” (round forms). Our tests require every published figure to be within 1% of π r² h.

FAQ

What sizes do Sonotubes come in?

Sonoco's Builder's Tube page lists 6, 8, 10 and 12 in diameters in 4, 8 and 12 ft lengths (“Available in 6" , 8" , 10" and 12" diameters in standard lengths of 4' , 8' and 12'”). Its round-forms brochure covers 6 to 36 in.

How many bags of concrete for a sonotube?

Bags = π × (diameter ÷ 24)² × length in ft ÷ the bag's yield, rounded up. For a 12 in × 4 ft tube: 6 bags of 80 lb Quikrete Concrete Mix.

How big and how deep should my deck footings be?

We don't size footings. Diameter, depth and any reinforcement come from your deck plans, an engineer or your local building department; this page only turns those sizes into concrete.

Sources

Sonoco: Sonotube Builder's Tube concrete forms (concrete chart) · fetched and reviewed 2026-11-10
Sonoco: Sonotube Round concrete forms brochure (concrete requirements table) · fetched and reviewed 2026-11-10
Quikrete: QUIKRETE Concrete Mix (No. 1101) data sheet · fetched and reviewed 2026-11-10
Sakrete: Sakrete Maximizer Concrete Mix technical data sheet · fetched and reviewed 2026-11-10

Volumes only. ConcreteMath calculates volumes, bag counts, weights and your own cost figures. It gives no structural or engineering advice and never sizes footings, piers, slabs or rebar: those come from your plans, an engineer or your local building department. Bag counts are estimates from each maker's published yield; actual use varies with hole shape, uneven ground, waste and mixing. Bulk weights are published ranges; your supplier's figure wins.