How to use it
- Enter your Sonotube tube diameter in inches (set to 8 by default).
- Enter the total height or hole depth in feet.
- Input the total number of tubes you plan to pour.
- Read your required 80-lb bags, cubic feet, and cubic yards instantly.
Pouring footings without an exact material count costs you time, money, and structural integrity. A cold joint from running out of mix mid-pour weakens your foundation, while buying random guesses clutters your site with wasted materials.
This calculator takes your tube diameter, depth, and total tube count to generate your exact volume requirements in cubic feet and cubic yards. It then divides your volume directly by the standard yield—0.6 cubic feet per 80-lb bag—to output the exact bag count you need to buy.
Use the cubic yard figure if you plan to order a ready-mix truck for bigger jobs, or use the 80-lb bag total for mixing on-site. Knowing your exact numbers keeps your project on schedule and prevents mid-pour supply runs.
Pro tips
- Add a 10% waste buffer to account for uneven trench bottoms, spillage, and tube flare.
- Always round fractional bag results up to the next full bag before buying.
- Consider ordering ready-mix delivery instead of hand-mixing if your total exceeds 1 cubic yard.
- Inspect tube cardboard for moisture damage before pouring, as soft walls can bulge and consume extra concrete.
Real-life examples
- Setting sturdy deck posts below the frost line with 4-foot deep 8-inch tubes.
- Pouring concrete pier footings for a backyard shed or detached workshop.
- Securing heavy-duty fence corner posts and gate pillars with cylindrical forms.
Case study
Marcus needed to pour four 4-foot-deep, 8-inch pier tubes for a raised deck. Instead of guessing and under-ordering, he plugged in his measurements. The tool revealed he needed 5.6 cubic feet—exactly ten 80-lb bags. He bought 11 bags to cover spillage, finished the pour in one continuous session, and eliminated a mid-afternoon supply run.