Concrete Tube Calculator (Sonotube)
Enter the diameter and height of your concrete form tube to see how many bags fill it.
Enter dimensions to see how many bags to buy.
Concrete needed
Bags to buy
Check the yield printed on your bag.
Default yields are for standard mixes. Some mixes differ.
Estimates only. Check your bag and local requirements before ordering.
Sonotube is a trademark of Sonoco. DIYAmount is not affiliated with Sonoco.
Bags for common tube sizes
| Diameter | 80 lb | 60 lb | 40 lb |
|---|---|---|---|
| 8 in | 3 | 4 | 6 |
| 10 in | 4 | 6 | 8 |
| 12 in | 6 | 8 | 12 |
| 16 in | 11 | 14 | 21 |
| 18 in | 13 | 18 | 26 |
| 24 in | 24 | 31 | 47 |
How the volume is figured
Volume = 3.1416 × (Diameter ÷ 24)² × Height × Quantity
Diameter is in inches and height is in feet. The calculator uses the full volume of the tube, adds waste, divides by what one bag makes and rounds up.
Buying by the yard instead? See how many bags are in a yard of concrete.
Questions
How many bags of concrete do I need for a form tube?
It depends on the diameter and height. Use the calculator above or the table of common sizes.
How many bags fill a 12 inch by 4 foot tube?
6 bags of 80 lb with 10% waste.
How many bags for an 18 inch tube?
At 4 feet tall, 13 bags of 80 lb with 10% waste.
Does the calculator subtract anything?
No. It uses the full volume of the tube.