Sonotube Concrete Calculator
This sonotube concrete calculator (tube form calculator) gives exact cylinder volumes for cardboard form tubes — deck piers, post bases and columns. Enter diameter, height and how many tubes you're filling.
How to Use This Calculator
- Enter your dimensions — feet for lengths, inches for thickness.
- Adjust the options — waste percentage, bag size and your local concrete price.
- Read your results — volume, bags, weight and cost update live as you type.
The Formula
Tube volume = π × (diameter ÷ 2)² × height × number of tubes Worked example: One 12 in × 4 ft sonotube: π × 0.5² × 4 = 3.14 ft³ ≈ 6 × 80 lb bags. An 8 in tube of the same height needs just 1.40 ft³ ≈ 3 bags.
Common quick references from this concrete calculator for sonotube forms: an 8 inch sonotube needs 0.35 ft³ per foot of height, a 10 inch 0.55 ft³/ft, a 12 inch 0.79 ft³/ft, and a 16 inch 1.40 ft³/ft.
That means a 4-ft-tall 12 inch sonotube takes about 6 × 80 lb bags, and an 8 sonotube of the same height about 3 bags. Filling several tube forms for a deck? Enter the count and the calculator totals bags across all of them.
Pour in one continuous lift where possible and rod or vibrate lightly to remove air pockets — tube forms show every void when stripped.
Frequently Asked Questions
Common questions about the sonotube concrete calculator.
How much concrete fills a 12 inch sonotube?
0.79 ft³ per foot of height. A 4 ft tube holds 3.14 ft³ — about 6 × 80 lb bags or 0.12 yd³.
How much concrete fills an 8 inch sonotube?
0.35 ft³ per foot. A 4 ft tube holds 1.40 ft³ — about 3 × 80 lb bags.
What sonotube sizes are standard?
6, 8, 10, 12, 14, 16, 18, 24, 30, 36 and 48 inch diameters, in lengths up to 12 ft. This tube calculator accepts any diameter.
Do sonotubes need a footing?
For decks and structures, yes — pour piers on a spread footing or use a flared-base form so loads distribute below frost depth.
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