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Canada

Sonotube Concrete Calculator

Enter the tube diameter in inches, the height in feet and how many tubes you are pouring. You get the 30 kg bags and the volume in cubic yards and m³. Post holes and bell footings work the same way.

What are you pouring?
Round column or tube form
Diameter Height

Tip: you can type feet and inches, like 10' 6", or metric with its unit, like 3.2 m.

Use your own prices (optional)

You need

– cu yd

–

Poured, it weighs about – kg.

Premixed bags

Bag Bags To carry Est. cost

Ready-mix truck

–

How we price

Link to this calculation Download estimate (PDF)

Your materials at a glance

How to calculate concrete

  1. Pick the tube. Diameter in inches: 8, 10 and 12 in are common for decks.
  2. Measure the height. In feet, from the bottom of the hole to the top of the tube.
  3. Use the cylinder formula. π × (diameter ÷ 2)² × height, with the diameter in feet.
  4. Multiply by the tubes. Then add 5% and divide by ½ cu ft for 30 kg bags.

Worked example: six 10 in sonotubes, 4 ft deep

  1. One tube: π × (10 ÷ 12 ÷ 2)² × 4 = 2.18 cu ft. Six tubes: 13.09 cu ft.
  2. Plus 5%: 13.74 cu ft = 0.51 cubic yards, or 0.39 m³.
  3. 30 kg bags: 28.

Concrete per 4 ft sonotube

Diameter Cubic feet m³ 30 kg bags
6 in 0.79 0.022 2
8 in 1.40 0.040 3
10 in 2.18 0.062 5
12 in 3.14 0.089 7
14 in 4.28 0.121 9
16 in 5.59 0.158 12
18 in 7.07 0.200 15
24 in 12.57 0.356 26

One tube 4 ft tall, no waste included. For other heights, scale the cubic feet.

Concrete formulas by shape

All measurements in feet; divide inches by 12 first. Results are in cubic feet.

Column / pier
π × (diameter ÷ 2)² × height
Post hole
(hole area − post area) × depth; round hole π × (diameter ÷ 2)², square hole width²
Bell footing
π × r² × pier height + π × bell height ÷ 3 × (R² + R × r + r²), with r = pier radius and R = bell radius

Cubic yards = cubic feet ÷ 27. Cubic metres = cubic feet ÷ 35.31.

Frequently asked questions

How many bags of concrete for a sonotube?

A 10 inch tube 4 ft tall holds about 2.2 cu ft: 5 bags of 30 kg. See the table for other sizes.

How deep should a sonotube be?

Below the frost line, often 4 ft (1.2 m) or more in Canada, and on undisturbed soil. Your municipality sets the depth for decks and additions.

Do I need a footing under a sonotube?

Deck and porch posts often need a wider base than the tube: a bell footing or a pad. Use "Bell footing" in the calculator for a tube with a flared base.

About the prices

Costs are estimated ranges with source and date, never a quote. Enter your local prices under "Use your own prices", or read how we estimate prices.