How much concrete is in a 12 inch Sonotube?

About 0.79 cu ft for every foot of height, so 3.14 cu ft (0.116 cu yd) in a tube 4 ft tall. That is 5.2 bags of 80 lb mix (0.6 cu ft each) or 7 bags of 60 lb mix (0.45 cu ft each) before waste. The table above lists the other common sizes.

How many bags of concrete do I need for a column?

Work out the volume (π × radius² × height), add about 10% for waste, and divide by what a bag makes: 0.6 cu ft for 80 lb, 0.45 cu ft for 60 lb, 0.3 cu ft for 40 lb. A 12 in column 4 ft tall takes about 5.8 80 lb bags including waste. For several columns, add them first and round up once: leftover concrete from one form fills the next.

When is ready-mix better than bags for columns?

Bags are practical for a few small columns. The default job needs 35 bags, about 0.77 cu yd, and a bag of 80 lb weighs 80 lb, so that is 2,800 lb of bags to mix by hand. As a rough guide, once a job passes about 1 cu yd (around 45 bags of 80 lb mix) a ready-mix truck or a rented mixer is usually less work, and many suppliers charge a short-load fee on small orders, so ask yours. The calculator shows a bagged-versus-delivered comparison under the result.

What tube sizes are available?

Sonotube Builder’s Tube comes in 6, 8, 10 and 12 in diameters in 4, 8 and 12 ft lengths, and larger round forms (14, 16, 18, 24 in and up) are sold for bigger columns and piers. Sizes are inside diameters, which is what the calculator takes. Cut a long tube to the height you need.

Does this include a bell or flared footing?

No. A column is worked as a plain cylinder of the tube diameter. A flared or bell-shaped base, or a footing pad under the column, takes extra concrete: add the pad with the concrete footing calculator, and ask your plans or building department for the size it needs.

Do I need to add the hole below ground?

Yes, if the concrete fills it. For a pier, the height is the whole length of the concrete from the bottom of the hole to the top of the tube, the part below ground included. An auger hole wider than the tube, or poured without a tube, takes more than the tube diameter says, so enter the hole diameter instead.

How much waste should I allow?

About 10% is a common allowance for spills, uneven hole bottoms and leftover in the mixer; use 5% for neat, level forms you can fill exactly. It is an estimate: round the bags up once for the job rather than for each column.

When can I take the forms off?

Forms on footings and walls typically come off after 24 to 48 hours in mild weather, once the concrete holds its shape and the edges no longer crumble; leave them on longer in cold weather. Keep a new wall braced, and put loads or backfill against it only as your plans or inspector allow, usually not before about 7 days. Full design strength comes at about 28 days.

How long does concrete take to cure?

Concrete sets in hours but keeps curing, gaining strength, for weeks. Typical planning figures: light foot traffic after 24 to 48 hours, normal use after about 7 days, and full design strength at 28 days, though it keeps hardening slowly after that. Keep it moist for at least the first 7 days (mist it, or cover it with plastic or a curing compound) and protect it from freezing: moisture and warmth are what let it reach its strength. Below about 50 °F (10 °C) curing slows, so plan on more days.

Concrete Column Calculator: How Much Concrete for Tube Forms?

Six concrete columns poured in 12 in tubes, 4 ft (48 in) tall, take 35 bags of 80 lb concrete mix, with 10% extra. Each column holds 3.14 cu ft (0.116 cu yd), so 18.8 cu ft (0.7 cu yd) for the job, or 0.77 cu yd with waste, the figure to give a ready-mix supplier. An 80 lb bag makes about 0.6 cu ft.

Figures based on the sources listed belowUpdated 2026-10-07How we calculate

Column shape

Tube diameter (in)

The inside diameter of the tube. Common sizes are 6, 8, 10, 12, 14, 16, 18 and 24 in; a 12 in tube is typical for a deck pier.

Column height (in)

The height of the concrete, bottom to top, in inches (4 ft = 48 in). For a pier, include the part below ground.

Waste allowance

Standard: spills and uneven holes (10%)Tight, level forms (5%)Exact (0%)Custom

Number of columns

Every column or pier poured in its own form.

Bag sizeThe bag count and cost range follow the size you pick. High-yield or lightweight mixes make more per bag, so check yours.

Price per bag (optional)

Buy 35 bags

0.70 cu yd + 10% waste = 0.77 cu yd

Concrete per column: 3.14 cu ft
Concrete for 6 columns (no waste): 18.8 cu ft
Ready-mix to order (with waste): 0.77 cu yd
Bags per column: 5.76 bags (waste included)

Low

$157.50

Expected

$210.00

High

$280.00

Includes 0.07 cu yd waste

How this number is calculated

0.70 cu yd + 10% waste = 0.77 cu yd ÷ 0.0222 cu yd per bag = 35 bags

0.8 cu yd — ~8% of a standard truck load

Bagged vs. Ready-mix delivery

Bagged (80 lb bags)

35 bags

$157.50–$280.00 (typ. $210.00)

Ready-mix delivery

0.8 cu yd

$167.51–$213.59 (typ. $186.71)

For ~0.8 cu yd, ready-mix delivery is usually cheaper and far less labor.

When can I build on it?

Pour date (optional)Pick the day you pour to see the dates.

Forms off24–48 hours
Build on it (light loads, as your plans allow)7 days
Full design strength28 days

Typical waits for ordinary concrete mix kept moist and above 50 °F (10 °C). They vary with the mix, temperature and curing: cold weather adds days, and fast-setting mixes shorten some waits. Follow the bag or your supplier.

Shopping list

Concrete mix (80 lb)
Round concrete tube form (Sonotube)
Post level
Mixing tub
Earth auger for pier holes
Rebar

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Concrete per column by tube size

Round tube forms by inside diameter, one column, no waste: concrete = π × radius² × height, worked by this calculator. Bags are shown to one decimal before rounding up; for a job, add the columns first and round up once.
Tube diameter	Cu ft per foot of height	Cu ft in a 4 ft column	Cu yd in a 4 ft column	80 lb bags (4 ft)	60 lb bags (4 ft)
6 in	0.2	0.79	0.029	1.3	1.7
8 in	0.35	1.4	0.052	2.3	3.1
10 in	0.55	2.18	0.081	3.6	4.8
12 in	0.79	3.14	0.116	5.2	7
14 in	1.07	4.28	0.158	7.1	9.5
16 in	1.4	5.59	0.207	9.3	12.4
18 in	1.77	7.07	0.262	11.8	15.7
24 in	3.14	12.57	0.465	20.9	27.9

Whole bags and ready-mix for 1 to 20 columns

12 in tubes 48 in tall, 10% waste, rounded up once for the job, worked by this calculator. The cubic yards include waste.
Columns	Cu yd to order (with waste)	80 lb bags	60 lb bags	40 lb bags
1	0.13	6	8	12
4	0.51	24	31	47
6	0.77	35	47	70
10	1.28	58	77	116
20	2.56	116	154	231

Concrete curing timeline

Typical waits after pouring ordinary concrete mix kept moist and above 50 °F (10 °C), counted in calendar days from the pour day. They vary with the mix, temperature and curing: cold weather adds days, and fast-setting mixes shorten some waits. Enter your pour date in the calculator for your own dates.
Milestone	Typical wait	Example: poured Sat, Oct 3
Forms off	24–48 hours	Sun, Oct 4 – Mon, Oct 5
Build on it (light loads, as your plans allow)	7 days	Sat, Oct 10
Full design strength	28 days	Sat, Oct 31

Methodology & assumptions

Each column is a cylinder, π × (diameter ÷ 2)² × height, taken at the inside diameter of the form (a 12 in tube is 0.785 sq ft of cross-section, or 0.79 cu ft per foot of height). For the default 12 in tube 48 in tall that is 3.14 cu ft. A square or rectangular form is length × width × height. The job's concrete is that times the number of columns; the waste you choose (10% by default, for spills and uneven holes) is added, and the total is divided by the bag yield and rounded up once for the whole job, not for each column. The same total in cubic yards, with waste, is the amount to order as ready-mix. Bag yields are Quikrete's published figures for Concrete Mix (No. 1101): 0.6, 0.45 and 0.3 cu ft for 80, 60 and 40 lb bags; other brands, and high-yield or lightweight mixes, differ, so check your bag. A column is treated as a plain cylinder: a bell or flared footing at the base, rebar and anchor bolts are not counted, and a pad under the column is a separate pour (use the concrete footing calculator). Tube forms are sold by inside diameter, and an auger hole wider than the tube takes more concrete than the tube alone. The metric toggle shows the tube diameter and height in cm, with the concrete in m³.

Quikrete Concrete Mix (No. 1101) data sheet: 80 lb ≈ 0.60 cu ft, 60 lb ≈ 0.45 cu ft, 40 lb ≈ 0.30 cu ft
Sonoco, Sonotube Builder’s Tube concrete forms brochure: 6, 8, 10 and 12 in diameters, 4, 8 and 12 ft lengths, for decks, posts and piers
Sonoco, Sonotube Concrete Forming Products brochure: larger round forms for columns and piers
Typical US retail prices for 40 to 80 lb concrete mix bags, 2026 (estimate)
Local building code and your plans or engineer for column size, depth, rebar and footing (the figures here are for the concrete only)
American Concrete Institute, ACI 308R guide to curing concrete: keep concrete moist for at least the first 7 days (ordinary portland cement mixes)
Portland Cement Association, Design and Control of Concrete Mixtures: moisture and temperature drive strength gain, which slows in cold weather; design strength is commonly specified at 28 days
Concrete Network, How Long Before You Can Drive on New Concrete?

How to calculate concrete for round columns

Count the columns. Count every column or pier that gets its own form.
Enter the tube diameter and height. Use the inside diameter of the tube (6, 8, 10, 12, 14, 16, 18 or 24 in are common) and the height of the concrete in inches, the part below ground included.
Work out the concrete per column. π × radius² × height, in cubic feet: radius and height in feet, or divide the cubic inches by 1,728.
Add the columns and the waste. Multiply by the number of columns, add about 10% for waste, and divide by 27 for cubic yards.
Convert to bags or ready-mix. Divide the cubic feet by the bag yield (0.6 cu ft for an 80 lb bag) and round up once. For a delivered order, give the supplier the cubic yards with waste.

Worked examples

Project	Result
6 columns in 12 in tubes, 48 in tall, 80 lb bags, 10% waste	35 bags of 80 lb mix: 3.14 cu ft per column, 18.8 cu ft (0.7 cu yd) in all
8 deck piers in 10 in tubes, 60 in tall, 80 lb bags, 10% waste	40 bags of 80 lb mix: 2.73 cu ft per column, 21.8 cu ft (0.81 cu yd) in all
4 square columns 12 in × 12 in, 96 in tall, 80 lb bags, 10% waste	59 bags of 80 lb mix: 8 cu ft per column, 32 cu ft (1.19 cu yd) in all
12 columns in 24 in tubes, 96 in tall, 60 lb bags, 10% waste	738 bags of 60 lb mix: 25.13 cu ft per column, 301.6 cu ft (11.17 cu yd) in all, so 12.3 cu yd of ready-mix is the better buy

Frequently asked questions

How much concrete is in a 12 inch Sonotube?: About 0.79 cu ft for every foot of height, so 3.14 cu ft (0.116 cu yd) in a tube 4 ft tall. That is 5.2 bags of 80 lb mix (0.6 cu ft each) or 7 bags of 60 lb mix (0.45 cu ft each) before waste. The table above lists the other common sizes.
How many bags of concrete do I need for a column?: Work out the volume (π × radius² × height), add about 10% for waste, and divide by what a bag makes: 0.6 cu ft for 80 lb, 0.45 cu ft for 60 lb, 0.3 cu ft for 40 lb. A 12 in column 4 ft tall takes about 5.8 80 lb bags including waste. For several columns, add them first and round up once: leftover concrete from one form fills the next.
When is ready-mix better than bags for columns?: Bags are practical for a few small columns. The default job needs 35 bags, about 0.77 cu yd, and a bag of 80 lb weighs 80 lb, so that is 2,800 lb of bags to mix by hand. As a rough guide, once a job passes about 1 cu yd (around 45 bags of 80 lb mix) a ready-mix truck or a rented mixer is usually less work, and many suppliers charge a short-load fee on small orders, so ask yours. The calculator shows a bagged-versus-delivered comparison under the result.
What tube sizes are available?: Sonotube Builder’s Tube comes in 6, 8, 10 and 12 in diameters in 4, 8 and 12 ft lengths, and larger round forms (14, 16, 18, 24 in and up) are sold for bigger columns and piers. Sizes are inside diameters, which is what the calculator takes. Cut a long tube to the height you need.
Does this include a bell or flared footing?: No. A column is worked as a plain cylinder of the tube diameter. A flared or bell-shaped base, or a footing pad under the column, takes extra concrete: add the pad with the concrete footing calculator, and ask your plans or building department for the size it needs.
Do I need to add the hole below ground?: Yes, if the concrete fills it. For a pier, the height is the whole length of the concrete from the bottom of the hole to the top of the tube, the part below ground included. An auger hole wider than the tube, or poured without a tube, takes more than the tube diameter says, so enter the hole diameter instead.
How much waste should I allow?: About 10% is a common allowance for spills, uneven hole bottoms and leftover in the mixer; use 5% for neat, level forms you can fill exactly. It is an estimate: round the bags up once for the job rather than for each column.
When can I take the forms off?: Forms on footings and walls typically come off after 24 to 48 hours in mild weather, once the concrete holds its shape and the edges no longer crumble; leave them on longer in cold weather. Keep a new wall braced, and put loads or backfill against it only as your plans or inspector allow, usually not before about 7 days. Full design strength comes at about 28 days.
How long does concrete take to cure?: Concrete sets in hours but keeps curing, gaining strength, for weeks. Typical planning figures: light foot traffic after 24 to 48 hours, normal use after about 7 days, and full design strength at 28 days, though it keeps hardening slowly after that. Keep it moist for at least the first 7 days (mist it, or cover it with plastic or a curing compound) and protect it from freezing: moisture and warmth are what let it reach its strength. Below about 50 °F (10 °C) curing slows, so plan on more days.

Handy tools

Feet and Inches Calculator: Turn a column height read off a tape, like 4 ft 7 1/2 in, into the decimal inches the height field takes.