Tube Form Concrete Calculator (Sonotube)
Find how many 30 kg bags fill your round tube forms. Sonotube is one brand, made by Sonoco. We are not linked to it. Any round tube works the same way.
Measure your project
Your answer
That makes 0.27 m³, or 0.36 cubic yards. We added 10% extra.
If you buy bags
A 30 kg bag makes 0.014 m³ (0.5 cubic foot), say Sakrete and Quikrete Canada.
If you order a truck (ready-mix)
Ask for 1.00 m³ (about 1.31 cubic yards). Ontario plant lists start at 1 m³, so we price at least that.
This answer is a guide. Piers hold up weight, so check your local building rules or ask a builder or engineer.
Which costs less?
But you must mix 20 bags by hand. That is 600 kg to lift.
Bag price: the middle of 5 Ontario stores, October 2026. Ready-mix: Ontario and Calgary lists. All before tax.
Quick answers
- 4 tubes, 10 in wide, 4 ft deep
- 20 bags of 30 kg, with 10% extra. That is 0.27 m³ of concrete.
- Concrete per foot of tube
- 8 in: 0.35 cubic feet (32.4 L per metre). 10 in: 0.55. 12 in: 0.79.
- How deep in Canada?
- At least 1.2 m (4 ft) in clay or unknown soil (Part 9). Winnipeg asks 1.8 m for decks over 1,300 mm up.
- Tube price
- About $14.23 for a 10 in × 4 ft tube at only 2 Ontario stores, before tax.
How to work it out
- Measure the tube width in inches and how deep it goes in feet.
- Take half the width in inches. Divide by 12 to get the radius in feet.
- Use the cylinder volume formula: 3.142 × radius × radius × depth. That gives cubic feet for one tube.
- Multiply by the number of tubes, then add 10% for spills.
- Divide by 0.5, what one 30 kg bag makes. Round up.
Radius: 10 ÷ 2 ÷ 12 = 0.417 ft
3.142 × 0.417 × 0.417 × 4 = 2.18 cubic feet per tube
2.18 × 4 tubes = 8.73. Add 10%: 9.6 cubic feet
9.6 ÷ 0.5 = 19.2, so 20 bags of 30 kg
Concrete in each tube size
A 12 in tube holds 2.3 times what an 8 in tube holds.
| Tube | Cubic feet per foot | Litres per metre | Bags for 4 ft (our maths) | Sakrete, per 122 cm |
|---|---|---|---|---|
| 6 in (152 mm) | 0.2 | 18.2 | 1.6 | 1.5 |
| 8 in (203 mm) | 0.35 | 32.4 | 2.8 | 3 |
| 10 in (254 mm) | 0.55 | 50.7 | 4.4 | 4.5 |
| 12 in (305 mm) | 0.79 | 73 | 6.3 | 6.5 |
0.5 cubic foot per 30 kg bag, with no extra. 122 cm is 48 in.
Sakrete's sheet counts in half bags, so it differs from ours by up to 0.2 of a bag.
A ready-mix truck brings at least 1 m³. That fills about 16 tubes of 10 in × 4 ft.
How deep to set tubes in Canada
The building code (Part 9) has no frost depth for each city. In clay or unknown soil, it asks for at least 1.2 m (4 ft).
A deck has no heated space under it. Then, in clay, go to 1.2 m or the city's frost depth, whichever is deeper.
| Place | Depth | Applies to |
|---|---|---|
| Calgary, AB | 1.2 m (4 ft) | Deck piles, 10 in or wider |
| Winnipeg, MB | 1.8 m (6 ft) | Decks with joists over 1,300 mm up |
| Manitoba (outside Winnipeg) | 1.8 m (6 ft) | Decks with joists over 600 mm up |
| Ottawa, ON | 1.5 m (5 ft) | Sample deck plan only |
| Carleton Place, ON (Ottawa area) | 1.2 m (47¼ in) | Decks that are not floating |
| Toronto, ON | 1.2 m (4 ft) | Decks; no city page found |
| Montreal, QC | 1.4 m (about 4 ft 7 in) | Terraces (one borough) |
| UBC Vancouver campus, BC | 450 mm (about 18 in) | A campus design rule |
| Edmonton, AB | 1.2 m (4 ft) | Decks; typical depth, but it depends on the soil |
| Halifax, NS | 1.2 m (4 ft) | Decks joined to the house or over 2 ft high |
Code: Part 9 (BC Building Code 2018 and Ontario Building Code 2024 text). Toronto, Montreal: search results only.
Low decks can skip it
A low "floating" deck is exempt. It is 1 storey, up to 55 m² (592 sq ft), with joists no more than 600 mm up.
It has no roof and isn't attached to the house.
Piers carry weight, so check your local building rules or ask a builder or engineer.
Tube prices and bell bases
A 12 ft yard tube makes 3 piers of 4 ft.
| Tube | 4 ft tube at a store | Per foot at yards (sellers) | 12 ft tube at yards |
|---|---|---|---|
| 8 in | $11.70 | $2.12 (3) | $25.44 |
| 10 in | $14.23 | $3.02 (2) | $36.24 |
| 12 in | $16.98 | $3.75 (3) | $45 |
Stores: only 2 in Ontario. Yards: only 2 or 3 sellers, so rough. Last column: price per foot × 12.
Bell bases for a wider footing
A bell base under the tube widens the footing.
| Base | Footing width | Takes tubes | Concrete | 30 kg bags |
|---|---|---|---|---|
| BF20 | 20 in (508 mm) | 6, 8 in | 49.6 L | 3.5 |
| BF24 | 24 in (610 mm) | 8, 10 in | 70.8 L | 5 |
| BF28 | 28 in (711 mm) | 10, 12 in | 92 L | 6.5 |
| BF36 | 36 in (914 mm) | 12, 14, 16, 18 in | 169.9 L | 12 |
A 24–29.5 in base costs about $35.69, the middle of 3 prices at 2 Ontario stores. A 36 in base is about $89.84 at 1 seller.
A plain 12 in tube has 0.073 m² of base. One Ontario town's deck guide asks for 0.11–0.30 m² for spans of 6–10 ft. A 24 in base gives 0.292 m², just under the top figure.
Questions people ask
How much concrete is in a 10 inch sonotube?
A 4 ft tube holds about 62 litres. That is 4.4 bags of 30 kg, so buy 5.
How many 30 kg bags fill a 12 inch tube?
Our maths gives 6.3 bags for 4 ft, so buy 7. Sakrete Canada prints 6.5 bags for each 122 cm.
Do I need a bell base under a tube form?
It depends on the deck. A plain 12 in tube has 0.073 m² of base. For beam and joist spans of 6–10 ft, one Ontario town asks 0.11–0.30 m². Ask your city.
What size tube do I need for deck piers?
Calgary asks for piles at least 10 in across. Ottawa's sample deck plan shows an 8 in pier on a 24 in footing.
How long are tube forms in Canada?
Yards mostly sell 12 ft tubes, and some sell 8 ft. Ontario big-box stores also stock 4 ft tubes.
How much does a tube form cost in Canada?
A 4 ft tube costs $11.70 (8 in) to $16.98 (12 in) before tax. That is the middle of only 2 Ontario stores.
Where our numbers come from
- Bag size: Sakrete Canada Concrete Mix (30 kg makes 0.014 m³, or ½ cubic foot)
- Bag sizes: Quikrete Concrete Mix, Canadian data sheet (30 kg = 14 L, 25 kg = 11.7 L)
- Fast-Setting mix: Quikrete data sheet (bag sizes and fence posts)
- Bags per tube and post, walk thickness: Sakrete Concrete Mix (Canada) data sheet
- Deck footings: Town of Carleton Place deck guideline (OBC 2024)
- Extra for spills: Sakrete slab calculator (10%)
- Store prices: Ontario Home Depot, RONA, Home Hardware and Chamberlain Timber Mart (Oct 2026)
- Tube forms in Canada: lengths and prices (Oct 2026; few prices)
- Bell footing forms: Bigfoot Systems product pages
- Bell footing forms: ICC-ES report ESR-2148 (Bigfoot, a US code report)
- Foundation depth: BC Building Code 2018, Section 9.12 (Table 9.12.2.2)
- Foundation depth: Ontario Building Code Table 9.12.2.2 (2012 text, third-party copy)
- Ontario Building Code 2024, Part 9 (ministry compendium)
- Deck footing depth: City of Calgary deck permit checklist (1.2 m)
- Deck footing depth: City of Winnipeg decks brochure (1.8 m)
- Deck footing depth: Manitoba building code guide 06 (1.8 m)
- Deck footing depth: City of Ottawa sample sundeck plan (5 ft, a drawing)
- Deck footing depth, Toronto: a deck builder's blog (search result only)
- Deck footing depth: Montreal borough terrace permit sheet (search snippet only)
- Frost depth: UBC Vancouver campus design guideline (450 mm)
- Deck footing depth: City of Edmonton Uncovered Deck Design Guide (Dec 2022)
- Deck footing depth: Halifax permit page
- Ready-mix price: the middle of 4 prices from 3 companies (25 MPa, Oct 2026, before tax)
- Small-load and winter fees: Dufferin Concrete 2026 price list (Ontario)
- Small-load fees: CBM Toronto-area price list
Made by BuildersCount. Last checked 4 Oct 2026.
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