| Hole diameter | Depth | Cubic feet (+10%) | 80 lb bags | 60 lb bags |
|---|---|---|---|---|
| 6 in | 24 in | 0.43 | 0.7 | 1.0 |
| 8 in | 24 in | 0.77 | 1.3 | 1.7 |
| 8 in | 36 in | 1.15 | 1.9 | 2.6 |
| 10 in | 36 in | 1.80 | 3.0 | 4.0 |
| 10 in | 42 in | 2.10 | 3.5 | 4.7 |
| 12 in | 42 in | 3.02 | 5.0 | 6.7 |
| 12 in | 48 in | 3.46 | 5.8 | 7.7 |
Rule of thumb
Holes should be about three times the post width and a third to half of the post’s above-ground height deep, below your frost line. A 4×4 post usually gets a 10–12 in hole.
For a whole fence line, pick Post holes in the concrete calculator and enter the number of holes.