How much concrete do I need for a sonotube?

π × radius² × height, in feet: a 12 inch tube 4 ft tall is 3.1416 × 0.5² × 4 = 3.14 cu ft, or 0.12 cu yd. Multiply by the number of tubes and add waste; the sonotube calculator does both and gives the bags and the ready-mix order.

How many bags of concrete for a 12 inch sonotube?

1.3 bags of 80 lb mix per foot of height (0.79 cu ft ÷ 0.60), so a 4 ft tube takes 5.2, which is 6 bags with 10% waste. Sonoco's Builder's Tube chart rounds the same tube to 0.80 cu ft and 1 1/3 bags of 80 lb per foot. In 50 lb fast-setting bags, a 4 ft tube is 8.4.

How much concrete for a 16 or 18 inch sonotube?

A 16 inch tube holds 1.40 cu ft per foot and an 18 inch tube 1.77 cu ft. A full 12 ft length, Sonoco's standard, is 0.62 cu yd and 0.79 cu yd, the figures in Sonoco's own table for round forms. Bags add up fast at that size: an 18 inch tube 4 ft tall already takes 12 bags of 80 lb.

What sizes do sonotubes come in?

Sonoco sells Sonotube Builder's Tube in 6, 8, 10, 12 inch diameters, 4, 8, 12 ft long, and Sonotube round forms from 6 to 36 inches in 12 ft lengths; larger columns use its commercial forms. The sizes are nominal, so measure the inside of your tube if the volume matters. Cut a tube to the height you need.

How do I calculate the volume of a concrete cylinder?

Volume = π × radius² × height, with every size in feet for cubic feet. The radius is half the diameter: a 10 inch cylinder has a radius of 5 inches, 0.417 ft. A 10 inch cylinder 3 ft tall is 3.1416 × 0.417² × 3 = 1.64 cu ft. Divide by 27 for cubic yards.

Should I use bags or ready-mix for sonotubes?

Bags for a few small tubes, a truck for many or large ones. Six deck piers of 12 inch tube 4 ft tall take 0.77 cu yd with 10% waste, 35 bags of 80 lb to mix by hand, or a 1.00 yd ready-mix order. Many suppliers have a minimum load or a short-load fee, so price both in the concrete cost calculator.

How do I add a footing under a sonotube?

Pick Square pad and enter its width and thickness, or pick Footing form and type the volume printed on the form's label, such as a bell-shaped plastic base the tube sits on. The calculator adds that volume under every tube. The footing's size comes from your plans or your local code, by the load and the soil.

How much concrete is in a sonotube in cubic meters?

π × radius² × height in meters: a 30 cm tube 1.2 m tall is 3.1416 × 0.15² × 1.2 = 0.08 m³, 85 L. Switch the calculator to metric to enter centimeters and count your own kilogram bag by the yield in liters on its label.

Sonotube Concrete Calculator

A 12 inch sonotube holds 0.79 cu ft of concrete per foot of height, so a 4 ft tube takes 3.14 cu ft, 5.2 bags of 80 lb mix before waste. Pick the tube size, enter the height and the number of tubes, and add a footing under each if your plans have one: you get the cubic feet and yards, the bags per tube and in total, and the ready-mix order.

Units

Tube size

Tube diameter (in)

Height of concrete

Number of tubesWaste allowance (%)

Footing under each tube

Tubes are sold by nominal inch sizes: measure yours if it matters. The footing's size comes from your plans or your local code.

0.77 cu yd of concrete for 6 tubes

Concrete per tube:: 3.46 cu ft
In total:: 0.77 cu yd (20.73 cu ft)
Without the waste allowance:: 0.70 cu yd (18.85 cu ft)
The tube per foot of height:: 0.79 cu ft
Ready-mix order:: 1.00 cu yd
80 lb bags:: 35 bags (5.8 per tube)
60 lb bags:: 47 bags (7.7 per tube)
50 lb fast-setting bags:: 56 bags (9.2 per tube)
40 lb bags:: 70 bags (11.5 per tube)

Posts set in the hole, with gravel: the fence post concrete calculator.
Bags against ready-mix at your prices: the concrete cost calculator.
Slabs, footings and steps: the concrete calculator.

How HomeMath calculates concrete for sonotubes

A sonotube is a cylinder, so HomeMath takes π × radius² × height: the diameter in inches ÷ 24 for the radius in feet, squared, × π × the height in feet. A footing under the tube adds its own volume: a square pad is side × side × thickness, and a footing form adds the volume printed on its label. × the number of tubes, plus the waste allowance (10% to start), ÷ 27 gives the cubic yards, and the ready-mix order rounds up to the next quarter yard. Bags are the volume ÷ the bag's yield, rounded up for the job and shown to one decimal per tube. Tube sizes are nominal, as Sonoco notes, so measure the inside if it matters. In metric, HomeMath converts meters and centimeters exactly (1 in = 2.54 cm) and shows the result in cubic meters, liters and square meters.

The published rules it uses: US customary units; metric conversion; premixed bag yields; post holes, fast-setting bags and tube forms. Their sources, and how HomeMath tests every result, are on the about page.

How much concrete do a tube and a set of deck piers take?

Each with 10% waste: the cubic yards, then the 80 lb bags.

One 12 in tube, 4 ft tall0.13 cu yd · 6 × 80 lb
6 deck piers, 10 in tubes 4 ft tall0.53 cu yd · 24 × 80 lb
9 deck piers, 12 in tubes 3 ft tall0.86 cu yd · 39 × 80 lb

How much concrete does a tube hold per foot?

Multiply the figure for your tube by its height in feet. The bags are per foot of height, before waste, so a 4 ft tube takes four times the number shown. Doubling the diameter quadruples the concrete: a 24 in tube holds four times as much as a 12 in one of the same height.

Concrete per foot of tube height, and bags per foot
Tube	Cubic feet	Cubic yards	80 lb	60 lb	50 lb fast-setting	40 lb
6 in	0.20 cu ft	0.007	0.33	0.44	0.52	0.65
8 in	0.35 cu ft	0.013	0.58	0.78	0.93	1.16
10 in	0.55 cu ft	0.020	0.91	1.21	1.45	1.82
12 in	0.79 cu ft	0.029	1.31	1.75	2.09	2.62
16 in	1.40 cu ft	0.052	2.33	3.10	3.72	4.65
18 in	1.77 cu ft	0.065	2.95	3.93	4.71	5.89
20 in	2.18 cu ft	0.081	3.64	4.85	5.82	7.27
24 in	3.14 cu ft	0.116	5.24	6.98	8.38	10.47

What do Sonoco's tube sizes hold?

Sonoco sells its Sonotube Builder's Tube, made for decks, fences, mailbox posts and swing sets, in 6, 8, 10, 12 in diameters, 4, 8, 12 ft long. The table gives the concrete in each full length and the 80 lb bags, rounded up, before waste; Sonoco's own chart rounds the volume per foot, given beside HomeMath's.

Builder's Tube sizes: cubic feet per foot, and a full tube with its 80 lb bags
Tube	Cu ft per foot	4 ft tube	8 ft tube	12 ft tube
6 in	0.196 (Sonoco: 0.20)	0.79 cu ft · 2 bags	1.57 cu ft · 3 bags	2.36 cu ft · 4 bags
8 in	0.349 (Sonoco: 0.35)	1.40 cu ft · 3 bags	2.79 cu ft · 5 bags	4.19 cu ft · 7 bags
10 in	0.545 (Sonoco: 0.55)	2.18 cu ft · 4 bags	4.36 cu ft · 8 bags	6.54 cu ft · 11 bags
12 in	0.785 (Sonoco: 0.80)	3.14 cu ft · 6 bags	6.28 cu ft · 11 bags	9.42 cu ft · 16 bags

A 12 in tube cut to 4 ft takes 3.14 cu ft, 5.24 bags of 80 lb, so 6 bags with 10% waste. An 8 in tube of the same height takes 1.40 cu ft, under half as much.

Its round forms run from 6 to 36 in in 12 ft lengths. At the larger sizes the concrete is counted in yards and the bags add up fast.

Larger tubes: cubic yards for a 4 ft pier and a full 12 ft length, before waste
Tube	4 ft tall	12 ft tall	80 lb bags, 4 ft
16 in	0.21 cu yd	0.62 cu yd	10
18 in	0.26 cu yd	0.79 cu yd	12
20 in	0.32 cu yd	0.97 cu yd	15
24 in	0.47 cu yd	1.40 cu yd	21

The 12 ft figures match the concrete table Sonoco prints for its round forms, which gives 0.785 cubic yards for an 18 in column 12 ft tall. Sizes are nominal, so measure the inside of your tube if the volume matters.

Should deck piers be poured from bags or a truck?

A few tubes are a bag job: mix them in a wheelbarrow, one tube at a time. 9 deck piers of 12 in tube 4 ft tall take 1.15 cu yd with 10% waste, which is 52 bags of 80 lb (4,160 lb to mix by hand) or a 1.25 yd ready-mix order. One cubic yard is 45 bags of 80 lb.

Sonoco recommends setting every tube for the job in advance and pouring them all at once. A truck makes that easy, but many suppliers have a minimum load or a short-load fee; the concrete cost calculator prices bags against ready-mix at your prices. Don't vibrate concrete in a Builder's Tube: Sonoco says it is not made for mechanical vibrators.

How do I work out the volume of a tube by hand?

A tube form is a cylinder, so its volume is π × radius² × height. Take a 10 in tube 3.5 ft tall:

Radius: 10 ÷ 2 = 5 in, ÷ 12 = 0.417 ft.
Area of the circle: 3.1416 × 0.417² = 0.545 sq ft.
Volume: 0.545 × 3.5 = 1.91 cu ft, or 0.07 cu yd.
Bags: 1.91 cu ft ÷ 0.60 = 3.18, so 4 bags of 80 lb before waste.

The same formula gives any round column, post hole or pier; the fence post concrete calculator also takes the post out of the hole and counts the gravel under it.

How much concrete does a footing under the tube add?

A deck pier often stands on a wider footing: a square pad poured at the bottom of the hole, or a plastic footing form the tube sits on, which the calculator takes by the volume printed on its label. The table gives a square pad under one tube.

Concrete in a square pad under one tube
Pad	6 in thick	8 in thick	12 in thick
16 × 16 in	0.89 cu ft	1.19 cu ft	1.78 cu ft
20 × 20 in	1.39 cu ft	1.85 cu ft	2.78 cu ft
24 × 24 in	2.00 cu ft	2.67 cu ft	4.00 cu ft

A 10 in tube 4 ft tall on a 24 × 24 in pad 8 in thick takes 4.85 cu ft before waste, 9 bags of 80 lb. The footing's size and depth, below the frost line, come from your plans or your local code, set by the load and the soil; HomeMath measures the concrete only.

How much concrete does a tube take in metric?

Switch the units to metric and the diameter, pad and thickness take centimeters and the height meters or centimeters; the tube size buttons fill in the inch sizes in centimeters, since tubes are sold by the inch. A 30 cm tube 1.2 m tall holds 0.08 m³ (85 L). Type your kilogram bag's weight and its yield in liters, and the calculator counts it too.

Frequently asked questions

How much concrete do I need for a sonotube?: π × radius² × height, in feet: a 12 inch tube 4 ft tall is 3.1416 × 0.5² × 4 = 3.14 cu ft, or 0.12 cu yd. Multiply by the number of tubes and add waste; the sonotube calculator does both and gives the bags and the ready-mix order.
How many bags of concrete for a 12 inch sonotube?: 1.3 bags of 80 lb mix per foot of height (0.79 cu ft ÷ 0.60), so a 4 ft tube takes 5.2, which is 6 bags with 10% waste. Sonoco's Builder's Tube chart rounds the same tube to 0.80 cu ft and 1 1/3 bags of 80 lb per foot. In 50 lb fast-setting bags, a 4 ft tube is 8.4.
How much concrete for a 16 or 18 inch sonotube?: A 16 inch tube holds 1.40 cu ft per foot and an 18 inch tube 1.77 cu ft. A full 12 ft length, Sonoco's standard, is 0.62 cu yd and 0.79 cu yd, the figures in Sonoco's own table for round forms. Bags add up fast at that size: an 18 inch tube 4 ft tall already takes 12 bags of 80 lb.
What sizes do sonotubes come in?: Sonoco sells Sonotube Builder's Tube in 6, 8, 10, 12 inch diameters, 4, 8, 12 ft long, and Sonotube round forms from 6 to 36 inches in 12 ft lengths; larger columns use its commercial forms. The sizes are nominal, so measure the inside of your tube if the volume matters. Cut a tube to the height you need.
How do I calculate the volume of a concrete cylinder?: Volume = π × radius² × height, with every size in feet for cubic feet. The radius is half the diameter: a 10 inch cylinder has a radius of 5 inches, 0.417 ft. A 10 inch cylinder 3 ft tall is 3.1416 × 0.417² × 3 = 1.64 cu ft. Divide by 27 for cubic yards.
Should I use bags or ready-mix for sonotubes?: Bags for a few small tubes, a truck for many or large ones. Six deck piers of 12 inch tube 4 ft tall take 0.77 cu yd with 10% waste, 35 bags of 80 lb to mix by hand, or a 1.00 yd ready-mix order. Many suppliers have a minimum load or a short-load fee, so price both in the concrete cost calculator.
How do I add a footing under a sonotube?: Pick Square pad and enter its width and thickness, or pick Footing form and type the volume printed on the form's label, such as a bell-shaped plastic base the tube sits on. The calculator adds that volume under every tube. The footing's size comes from your plans or your local code, by the load and the soil.
How much concrete is in a sonotube in cubic meters?: π × radius² × height in meters: a 30 cm tube 1.2 m tall is 3.1416 × 0.15² × 1.2 = 0.08 m³, 85 L. Switch the calculator to metric to enter centimeters and count your own kilogram bag by the yield in liters on its label.