Sonotube Calculator

US & Canada

Pick your tube size and depth to get the concrete and bags for every footing on the job.

Your footings

1. Tube size

ft
tubes

Use the full height you will fill: the depth below grade plus any tube left above it. Footing depth is set by your local frost depth.

2. Allowance

%

10% covers spillage and a hole dug wider than the tube at the bottom.

Result

0

Bags to buy

Bag yields are the figures printed on standard concrete mix bags. Over about half a cubic yard, compare the price of a ready-mix delivery.

How the sonotube maths works

  • Volume of one tube = π × (diameter ÷ 2)² × depth
  • Total = volume × number of footings × (1 + allowance)
  • Bags = total ÷ bag yield, rounded up

Bag yields are the figures printed on standard concrete mix: 0.45 cu ft for a 60 lb bag, 0.6 cu ft for 80 lb, and 12.7 L for a 30 kg bag sold in Canada. Check the bag you buy, since yields vary a little by product.

Bags of concrete per sonotube

One footing, with 10% extra.

Bags of concrete per sonotube by diameter and depth
Tube Depth Concrete 80 lb 60 lb 30 kg
8 in 3 ft 1.15 cu ft 2 3 3
8 in 4 ft 1.54 cu ft 3 4 4
10 in 3 ft 1.8 cu ft 3 4 5
10 in 4 ft 2.4 cu ft 4 6 6
12 in 3 ft 2.59 cu ft 5 6 6
12 in 4 ft 3.46 cu ft 6 8 8
16 in 3 ft 4.61 cu ft 8 11 11
16 in 4 ft 6.14 cu ft 11 14 14
18 in 3 ft 5.83 cu ft 10 13 13
18 in 4 ft 7.78 cu ft 13 18 18
24 in 3 ft 10.37 cu ft 18 24 24
24 in 4 ft 13.82 cu ft 24 31 31

Before you pour

  • Depth comes first. Footings go below your local frost depth. See frost depth in Canada.
  • Bell footings (a wider plastic base under the tube) hold more concrete than the tube alone. Add the base's volume from its label.
  • Mix only what you can place. For more than about half a cubic yard, a ready-mix truck can be cheaper than bags and far less work.

Common questions

How many bags of concrete for a 12 inch sonotube?
A 12 in tube 4 ft deep holds 3.14 cu ft. With 10% extra that is 6 bags of 80 lb, 8 of 60 lb, or 8 of 30 kg.
How many bags of concrete for an 8 inch sonotube?
An 8 in tube 4 ft deep holds 1.4 cu ft: 3 bags of 80 lb or 4 of 60 lb with 10% extra.
How many bags of concrete for a 10 inch sonotube?
A 10 in tube 4 ft deep holds 2.18 cu ft: 4 bags of 80 lb, 6 of 60 lb, or 6 of 30 kg with 10% extra.
How much concrete for 9 deck footings?
Nine 10 in tubes 4 ft deep take 21.6 cu ft (0.8 cubic yards) with 10% extra, or 36 bags of 80 lb.
How much concrete for a 12 inch tube 1.2 m deep?
A 12 in (305 mm) tube 1.2 m deep holds 88 litres. With 10% extra that is 8 bags of 30 kg, or 10 of 25 kg.
How do you calculate concrete for a sonotube?
Volume = π × radius² × height. Work in feet: a 12 in tube has a 0.5 ft radius, so each foot of depth holds 3.1416 × 0.5² = 0.785 cu ft. Divide by the bag yield (0.6 cu ft for an 80 lb bag) and round up.
How deep should sonotubes go?
Below the frost line where you live, which your building department sets. Canadian codes require 1.2 m (4 ft) for unheated footings on clay or undefined soil unless frost goes deeper; see our frost depth page for city figures.
What size sonotube do I need for a deck?
It depends on the load each footing carries and your soil, so the deck's design or your local deck guide decides it. This calculator handles the concrete once you know the size.