Concrete pier and tube calculator
Enter the tube width and depth, then tell us how many piers you're pouring. For each pier, you'll see the number of bags and its volume in cubic feet.
Concrete for each foot of form tube
| Tube | Cubic feet per foot | 80 lb bags per foot | 60 lb bags per foot | 80 lb bags for a 4 ft pier |
|---|---|---|---|---|
| 6 in | 0.20 | 0.3 | 0.4 | 2 |
| 8 in | 0.35 | 0.6 | 0.8 | 3 |
| 10 in | 0.55 | 0.9 | 1.2 | 4 |
| 12 in | 0.79 | 1.3 | 1.7 | 6 |
| 14 in | 1.07 | 1.8 | 2.4 | 8 |
| 16 in | 1.40 | 2.3 | 3.1 | 11 |
| 18 in | 1.77 | 2.9 | 3.9 | 13 |
| 24 in | 3.14 | 5.2 | 7.0 | 24 |
Extra isn't counted in the per-foot numbers. For a 4 ft pier, the column adds 10%. Bag yields: Sakrete High-Strength Concrete Mix, plus Quikrete Concrete Mix No. 1101. A 40 lb bag gives 0.30 cu ft, a 50 lb bag 0.375 cu ft, a 60 lb bag 0.45 cu ft and an 80 lb bag 0.60 cu ft.
Sonotube concrete calculator by the foot
For a tube, concrete grows in proportion to the square of its width. Per foot, a 12 in tube holds 44% more than a 10 in tube and 4 times as much as a 6 in tube. Check the size on the tube before you buy bags.
A deck resting on 12 in tubes measuring 4 ft in depth calls for 24 of the 80 lb bags at 4 piers, 35 at 6 and 52 at 9. Your 9 piers take 1.15 cubic yards, an amount big enough that a small ready-mix load starts making sense.