How to use it
- Enter the sonotube diameter (18 in), height in feet, and the number of tubes.
- Click “Calculate” to see volume in cubic feet, cubic yards, and required 80‑lb bags.
- Review the bag count and add a waste allowance before ordering.
This tool converts the dimensions of a standard 18‑inch sonotube into the exact amount of concrete you’ll need, showing the result in cubic feet, cubic yards, and the number of 80‑lb bags. Knowing the bag count up front prevents last‑minute trips to the store and helps you order the right amount, saving time and money. The calculator first determines the tube’s volume from the diameter and depth you provide, then divides that volume by the 0.6 cf per bag constant to give a realistic bag estimate. The cubic‑yard figure lets you compare to delivery truck capacities, while the cubic‑foot total is useful for project documentation. All results appear instantly, so you can adjust dimensions or quantity and see the impact on material needs without any guesswork.
Pro tips
- Add 5‑10% extra bags for spillage and settling.
- Round up the bag total; you can’t buy a fraction of a bag.
- Order the bags in full pallets to qualify for bulk discounts.
- Double‑check the height measurement; a common mistake is using inches instead of feet.
Real-life examples
- A contractor estimating concrete for a new driveway footings with multiple 18‑inch sonotubes.
- A DIY homeowner planning a shed foundation and needing exact bag counts to avoid over‑ordering.
- A landscape designer calculating material for a decorative concrete wall using sonotubes.
Case study
Mike needed concrete for ten 18‑inch sonotubes, 3 ft deep each. Using the calculator, he saw he required 180 bags, added a 5% waste factor, and ordered 190 bags—avoiding a costly shortfall and saving a trip back to the supplier.