: The hole should typically be three times the width of the post (e.g., a 12-inch diameter hole for a 4x4 post) to allow for sufficient concrete or gravel packing.
: Most builders recommend burying one-third of the total post length in the ground. For a standard 6-foot fence, the post should be at least 2 feet deep. 22084mp4
If you are instead asking about the technical specifications for a "deep post" (as in a structural fence post): : The hole should typically be three times