Quikrete’s rule
Quikrete’s guide to setting posts says:
- Hole depth: 1/3 to 1/2 of the post’s above-ground height, plus 6 in.
- Hole width: about 3 times the post width.
- Gravel: about 6 in in the bottom for drainage.
- Fill: concrete up to 3 to 4 in below ground level, then soil, so water runs away from the post.
For a 6 ft fence that is a hole 2 to 3 ft deep plus gravel.
Frost
In places where the ground freezes, set posts below the frost line or they can heave. Your building department knows the local depth.
Concrete per post
Use the post hole concrete calculator.
Sources
Sources last checked 1 November 2026.
