Sonotube Calculator
Calculate concrete volume needed for sonotube columns, footings, and piers. Estimate concrete bags and project cost.
Concrete Volume
Bags Needed
Cost Estimate
Project Summary
Total volume: -
With waste ({(isset($wasteFactor) ? $wasteFactor : 10)}%): -
Total bags: -
Recommended order: -
Frequently Asked Questions
What is a sonotube?
A sonotube is a cardboard concrete form used to create cylindrical concrete columns, piers, and footings. They are commonly used for deck supports, fence posts, lamp posts, and structural foundations. The tubes are placed in excavated holes and filled with concrete.
How much concrete do I need for a sonotube?
Concrete volume for a sonotube is calculated using the formula for cylinder volume: Volume = π × r² × height. Use our calculator above for accurate results based on your tube diameter and height.
How do I calculate sonotube concrete?
To calculate sonotube concrete:
- Measure the tube diameter (in inches or cm)
- Measure the tube height/depth (in inches or cm)
- Calculate radius = diameter ÷ 2
- Volume = 3.1416 × radius² × height
- Convert to cubic feet or cubic yards
How many bags of concrete per sonotube?
The number of bags depends on tube size and bag weight. For example:
- 8" diameter × 36" deep: ≈ 2 bags (60 lb)
- 10" diameter × 36" deep: ≈ 3 bags (60 lb)
- 12" diameter × 36" deep: ≈ 4 bags (60 lb)
- 16" diameter × 48" deep: ≈ 10 bags (60 lb)
How much does a sonotube cost?
Sonotube prices vary by size and location:
- 8" × 4' tube: $10-15
- 10" × 4' tube: $15-20
- 12" × 4' tube: $20-25
- Concrete cost: $5-10 per 60 lb bag
How deep should a sonotube be?
Sonotube depth depends on the application:
- Deck posts: Below frost line (typically 36-48")
- Fence posts: 24-36" deep
- Light poles: 48-60" deep
- Structural columns: Per engineering specs
What size sonotube for a 4x4 post?
For a 4×4 wooden post, use a 10" or 12" diameter sonotube. This provides 3-4 inches of concrete around the post for adequate support and durability.
How many cubic feet in a 12" sonotube?
A 12" diameter (1 ft diameter) sonotube with 1 ft height contains 0.785 cubic feet. Formula: π × (0.5 ft)² × 1 ft = 0.785 cu ft.
Do sonotubes need rebar?
Yes, for structural applications, rebar should be used inside sonotubes to reinforce the concrete column. Typically, 3-4 vertical rebar pieces with horizontal ties are recommended for load-bearing columns.
How long do sonotubes last in the ground?
Sonotubes are designed for single use as concrete forms. The cardboard is removed or left to decompose after concrete cures (2-7 days). The concrete column itself lasts decades when properly mixed and cured.