How much concrete for a 6 inch Sonotube 4 feet long?

Data checked October 2026

Short answer

A 6 in Sonotube 4 ft long holds 0.79 cu ft of concrete — 2 × 80-lb bags or 2 × 60-lb bags.

A 6 in tube holds 0.196 cu ft per foot: π × (6 ÷ 24 ft)² = 0.196; × 4 ft = 0.79 cu ft.
Quik-Tube's data sheet lists 2 × 80-lb or 2 × 60-lb per 4 ft tube — our 2 / 2 come from the same geometry.
Buy 2 × 80-lb bags with the usual 10% cushion (about $12.94).
Dig a 12 in hole (twice the tube) and buy 1 × 4 ft tube.
6 in tubes suit light loads — Quik-Tube lists mailboxes, lamps and fence posts among its uses.

Adjust it to your exact job

Tube size

Diameter

Sonotube sizes include 6, 8, 10, 12, 14, 16, 18, 24 in; Quik-Tube comes in 8, 10 and 12 in.

Exact diameter

= 6"

How many?

Concrete heightwhole tube

= 4' · 1.22 m

Above groundpart of it

= 6"

Footing under the tube

Pour a footing first

Quik-Tube method: 2 in of gravel, a 4–6 in footing as wide as the hole (2× the tube), then set the tube on it.

You need

2× 80-lb bags

1.3 bags per column · 0.03 yd³ including 10% extra · 160 lb

Per column: 0.79 ft³0.196 ft³ per foot of tube
Total concrete: 0.03yd³before waste
Hole to dig: 12in2× the tube diameter (Quik-Tube)
Bottom below grade: 3' 6"compare with your frost depth

Check against the tube makers

Bags per column, whole bags, no waste
Per column	60-lb	80-lb
This calculator (geometry)	2	2
Quik-Tube data sheet	2	2

All bag sizes for the job

Bags needed by size
Bag	Bags	Est. cost
40 lb · 0.3 ft³	3	—
50 lb · 0.375 ft³	3	—
60 lb · 0.45 ft³	2	$9.70
80 lb · 0.6 ft³	2	$12.94

Footing depth

Deck and porch footings must sit at least 12 in below undisturbed ground (IRC R507.3.2 / R403.1.4) and below your local frost depth. Builder's-grade tubes stay in place — Sonoco notes they are not designed to be stripped.

Timeline for standard 4000 psi mix

Walk on: 24 hours
Light loads / posts: 24 hours
Keep moist (cure): 5 days ≥70°F · 7 days at 50–70°F
Protect from freezing: 48 hours

Shopping list

2 bags Standard 4000 psi mix — 80-lb bags$12.94
1 tubes 6 in form tube, 4 ft
1 pcs Post bases or anchor bolts, set in the wet concrete
3 gal Clean water for mixing2–2 gal; start low, never exceed the max

Estimated total$12.94

Cost estimate

Tap a price to use your store's

80-lb Standard 4000 psi mix
2 bags × $
$12.94

Materials total$12.94

Typical U.S. big-box prices checked 2026. Tap any price to enter your store's.

Did this answer your question?

Compare

6 in tube at other lengths

Length	Cu ft per tube	80-lb per tube	60-lb per tube
2 ft	0.39	1	1
3 ft	0.59	1	2
4 ft ←	0.79	2	2
5 ft	0.98	2	3
6 ft	1.18	2	3
8 ft	1.57	3	4

How this was worked out

Round forms are cylinders: area = π × radius². A 6 in tube has a 3 in radius, so π × 3² = 28.3 sq in ÷ 144 = 0.196 sq ft. Multiply by the length in feet for cubic feet.

0.79 cu ft ÷ 0.6 cu ft per 80-lb bag = 1.31, and ÷ 0.45 per 60-lb bag = 1.75. Tube tables round each tube up — here that leaves most of a bag over, so on several tubes round the total instead.

At 0.03 yd³ this is a bag job: a truck's 1 yd minimum plus fees would cost about $485.

The full method, material data and tips are on the main sonotube & column concrete calculator page.

Similar jobs

Other sizes people check

Sources

Data behind this answer

Quikrete QUIK-TUBE Building Form No. 6922 — technical data sheet — Table 1 bags per 1–4 ft of 6/8/10/12 in tube; hole 2× tube diameter; 2 in gravel and a 4–6 in footing; brace at 2 ft above grade; up to 3 ft above grade · checked October 2026
Sonoco Sonotube Builder's Tube — bags per 4 ft: 8 in 4×60/3×80, 10 in 5/4, 12 in 8/6, 16 in 13/10; below grade and up to 3 ft above · checked October 2026
Home Depot Sakrete 48 in form tubes — price history (Glassit) — 8 in × 48 in $10.88, 10 in × 48 in $14.48 (Jul 13, 2026, one tracked store) · checked October 2026
Quikrete Concrete Mix No. 1101 — technical data sheet — bag yields (80 lb = 0.60 cu ft, 60 lb = 0.45, 50 lb = 0.375, 40 lb = 0.30), water per bag, curing times; post method: 6 in of dry mix in the hole bottom, 24 h before strain · checked October 2026
Home Depot & Lowe's listings — Quikrete 80 lb Concrete Mix — $5.98–$6.98 per 80-lb bag; $5.93 bulk tier at 42+ bags; 42 bags per pallet; Fast-Setting 50 lb $7.97 · checked October 2026
Published 2026 ready-mix plant price sheets (e.g. Gehring Concrete) — $146–$285 per yd³ before fees; short-load fees $50–$200 · checked October 2026
International Residential Code 2021 — R403.1 footings & Table R403.1(1) — 12 × 6 in minimum footing, width by soil bearing, 12 in below undisturbed ground, 3 in cover over bars cast against earth; deck footings R507.3 · checked October 2026

Short answer

A 6 in Sonotube 4 ft long holds 0.79 cu ft of concrete — 2 × 80-lb bags or 2 × 60-lb bags.

A 6 in tube holds 0.196 cu ft per foot: π × (6 ÷ 24 ft)² = 0.196; × 4 ft = 0.79 cu ft.

Quik-Tube's data sheet lists 2 × 80-lb or 2 × 60-lb per 4 ft tube — our 2 / 2 come from the same geometry.

Buy 2 × 80-lb bags with the usual 10% cushion (about $12.94).

Dig a 12 in hole (twice the tube) and buy 1 × 4 ft tube.

6 in tubes suit light loads — Quik-Tube lists mailboxes, lamps and fence posts among its uses.

Adjust it to your exact job

Tube size

Diameter

Sonotube sizes include 6, 8, 10, 12, 14, 16, 18, 24 in; Quik-Tube comes in 8, 10 and 12 in.

Exact diameter

= 6"

How many?

Concrete heightwhole tube

= 4' · 1.22 m

Above groundpart of it

= 6"

Footing under the tube

Pour a footing first

Quik-Tube method: 2 in of gravel, a 4–6 in footing as wide as the hole (2× the tube), then set the tube on it.

You need

2× 80-lb bags

1.3 bags per column · 0.03 yd³ including 10% extra · 160 lb

Per column: 0.79 ft³0.196 ft³ per foot of tube
Total concrete: 0.03yd³before waste
Hole to dig: 12in2× the tube diameter (Quik-Tube)
Bottom below grade: 3' 6"compare with your frost depth

Check against the tube makers

Bags per column, whole bags, no waste
Per column	60-lb	80-lb
This calculator (geometry)	2	2
Quik-Tube data sheet	2	2

All bag sizes for the job

Bags needed by size
Bag	Bags	Est. cost
40 lb · 0.3 ft³	3	—
50 lb · 0.375 ft³	3	—
60 lb · 0.45 ft³	2	$9.70
80 lb · 0.6 ft³	2	$12.94

Footing depth

Timeline for standard 4000 psi mix

Walk on: 24 hours
Light loads / posts: 24 hours
Keep moist (cure): 5 days ≥70°F · 7 days at 50–70°F
Protect from freezing: 48 hours

Shopping list

2 bags Standard 4000 psi mix — 80-lb bags$12.94
1 tubes 6 in form tube, 4 ft
1 pcs Post bases or anchor bolts, set in the wet concrete
3 gal Clean water for mixing2–2 gal; start low, never exceed the max

Estimated total$12.94

Cost estimate

Tap a price to use your store's

80-lb Standard 4000 psi mix
2 bags × $
$12.94

Materials total$12.94

Typical U.S. big-box prices checked 2026. Tap any price to enter your store's.

Length

Cu ft per tube

80-lb per tube

60-lb per tube

2 ft

0.39

3 ft

0.59

4 ft ←

0.79

5 ft

0.98

6 ft

1.18

8 ft

1.57

How this was worked out

Round forms are cylinders: area = π × radius². A 6 in tube has a 3 in radius, so π × 3² = 28.3 sq in ÷ 144 = 0.196 sq ft. Multiply by the length in feet for cubic feet.

0.79 cu ft ÷ 0.6 cu ft per 80-lb bag = 1.31, and ÷ 0.45 per 60-lb bag = 1.75. Tube tables round each tube up — here that leaves most of a bag over, so on several tubes round the total instead.

At 0.03 yd³ this is a bag job: a truck's 1 yd minimum plus fees would cost about $485.

The full method, material data and tips are on the main sonotube & column concrete calculator page.