Concrete for a 8 inch tube, by height
A 8 in tube is used for mailbox, light and small fence posts, and light deck piers. The "with waste" column adds 10%, and bag counts are for one tube.
| Height | One tube | With waste | 80 lb bags | 60 lb bags | 50 lb bags |
|---|---|---|---|---|---|
| 2 ft | 0.70 ft³ | 0.77 ft³ | 2 | 2 | 3 |
| 3 ft | 1.05 ft³ | 1.15 ft³ | 2 | 3 | 4 |
| 4 ft | 1.40 ft³ | 1.54 ft³ | 3 | 4 | 5 |
| 5 ft | 1.75 ft³ | 1.92 ft³ | 4 | 5 | 6 |
| 6 ft | 2.09 ft³ | 2.30 ft³ | 4 | 6 | 7 |
| 8 ft | 2.79 ft³ | 3.07 ft³ | 6 | 7 | 9 |
For several tubes (4 ft each)
A deck often needs 4 to 12 footings, so the numbers add up:
| Number of tubes | Concrete (with waste) | Cubic yards | 80 lb bags |
|---|---|---|---|
| 1 tube | 1.5 ft³ | 0.06 yd³ | 3 |
| 4 tubes | 6.1 ft³ | 0.23 yd³ | 11 |
| 6 tubes | 9.2 ft³ | 0.34 yd³ | 16 |
| 9 tubes | 13.8 ft³ | 0.51 yd³ | 24 |
| 12 tubes | 18.4 ft³ | 0.68 yd³ | 31 |
Past about 15 to 20 bags, it is worth pricing a small ready-mix delivery. See the concrete bags guide.
Want to change anything else? The calculator above is the full Sonotube (Concrete Tube) Calculator: edit any number and the results update instantly.
Tools & materials for this project
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Frequently asked questions
How much concrete in a 8 inch sonotube?
0.35 ft³ for every foot of height. A 4 ft tube holds 1.40 ft³, and with 10% waste you need 3 bags of 80 lb.
How many bags of concrete for a 8 inch tube, 4 feet deep?
3 bags of 80 lb, 4 bags of 60 lb or 5 bags of 50 lb, including 10% waste.
How deep should a 8 inch footing be?
Footings must usually reach below the frost line, and your building plans or local code set the depth and diameter, so use the numbers from your plans.
Related sizes and guides
Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.