Sonotube and Column Calculator
Concrete for a round column or post hole, which is what a Sonotube form holds: volume from the inside diameter of the tube and the depth it is set to.
A Sonotube is sold by its inside diameter, and that is the figure to enter — a 12 in tube holds a 12 in column, not 12 in of cardboard. Depth is measured from the bottom of the hole, including the part below grade, because the whole tube gets filled.
With hole diameter 1 ft, height 4 ft, waste allowance 10 percent, price per cubic yard 145 usd, concrete comes to 0.13 cu yd — concrete needed. It is reached in 8 steps, the last of which is 3.4557519 / 27, and each one is printed on the page with its numbers filled in. The formula is the one published by American Concrete Institute, not an approximation fitted to it.
Formula and sources checked · How we check
- Volume
3.142 cu ft- Volume with waste
3.1415927 * (1 + 10 / 100)3.456 cu ft- Concrete needed
3.4557519 / 270.128 cu yd- Cubic meters
0.1279908 * 0.76455490.098 m3- 60 lb bags (0.45 cu ft each)
ceil(3.4557519 / 0.45)8 bags- 80 lb bags (0.60 cu ft each)
ceil(3.4557519 / 0.6)6 bags- Weight of the pour
0.1279908 * 4050518.363 lbs- Ready-mix cost at that price
0.1279908 * 14518.559
Several at once
A job is rarely one of anything. Work out the first, add it, change the figures and add the next — the list keeps what each line was, and totals them.
How do you stop the tube floating?
Wet concrete pushes a form upward as it fills. Brace the tube at the top and backfill around it before pouring, and fill in one go rather than in lifts. A tube that rises an inch mid-pour leaves a cold joint at precisely the height the load passes through.
What about the bell at the bottom?
Many footings flare below the tube into a wider pad, and that volume is not in the figure above — it is the straight cylinder only. A 24 in bell under a 12 in tube adds roughly a cubic foot on its own, which is a bag and a half you would otherwise be short.
The formula
- Volume
shape_slab * (length * width * thickness / 12) + shape_circle * (pi * pow(diameter / 2, 2) * thickness / 12) + shape_footing * (footing_length * footing_width * depth / 12) + shape_column * (pi * pow(hole_diameter / 2, 2) * height) + shape_wall * (wall_length * wall_height * wall_thickness / 12) + shape_stairs * (stair_width * rise / 12 * run / 12 * steps_count * (steps_count + 1) / 2) - Volume with waste
cubic_ft * (1 + waste / 100) - Concrete needed
cubic_ft_waste / 27 - Cubic meters
cubic_yards * 0.764554857984 - 60 lb bags (0.45 cu ft each)
ceil(cubic_ft_waste / 0.45) - 80 lb bags (0.60 cu ft each)
ceil(cubic_ft_waste / 0.60) - Weight of the pour
cubic_yards * 4050 - Ready-mix cost at that price
cubic_yards * price
Formula from American Concrete Institute, Portland Cement Association.
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