What size earth auger bit do you use for a 4x4 fence post?

[captbentley]

A 4x4 post is usually 3.5” x 3.5” which is just under 5” corner to corner.
if you haven’t purchased the auger, 8” is probably the most useful. A 6”auger will work fine.
A deeper hole will give more rigidity and can be backfilled with fine gravel or sand.

if you are in the market, after reading a review in Farm Show, I purchased a Ryobi 40 volt machine which came with one battery , a charger, and an 8” auger. I also bought a set of extensions. it is powerful and can do many holes on a single charge. it is reversible and much safer to use than a gas unit.

 

[jagster936]

Second that. Ryobi is an excellent machine. I used it to plant line of shrubs makes 1000x faster.

 

[Jimbo16720]

I've put 4x4 and 4x6 in with a 6" or 9" auger and quikmix and they've been in for years.

 

[thecatsandi]

I've seen 3x the size online but nobody seems to do that in real life. What size bit would you use for a 4x4 post? I will use either concrete or the foam stuff, probably the foam, so maybe the hole should be smaller diameter?

I have a 10" auger. this leaves room for concrete, gravel or dirt. This will also allow you to get the post strait is the hole is not quite vertical.

 

[mopardude318]

I only have one size. 12” auger seems to work for most things.