If you've ever built, or planned to build, a fence, then you've probably run across the issue of how long your fence posts should be; particularly if you weren't using a pre-fabricated system. With little to no experience, choosing the right length fence posts can be a confusing issue. Luckily, there is an easy to remember rule of thumb that many professional fence installers use to determine the height of their posts.
How Long Should My Fence Posts Be?
In general, 1/3 - 1/2 of the above ground height of your fence should be below ground, with a minimum of 2 ft. What this means in practice is that if you have a 4' high fence, your posts should be 6' with 2' below ground. If your fence is 6', then you should use 8 1/2' - 9' posts with 2 1/2' - 3' below ground.
If you follow the guideline above - for most standard fence systems - your posts should be deep enough to provide strength and stability for your fence. However, if you live in an area of high wind or extreme cold, you may want to opt for a longer post, because it will make your fence less vulnerable to the elements. On the other hand, if you are installing an light ornamental system in a low wind area, then you may be able to get away with shorter posts; although longer posts won't hurt.
Product Note:
If you plan to use a drivable post anchor like
Oz-Posts to install your fence, then the Oz-Post is the underground extension of your fence post, so a 6' tall fence should have a 3' Oz-Post and 6' wood, vinyl, aluminum, or steel post.
