Fence Post Length Calculator
Find the total post length you need to buy based on your desired fence height and burial depth.
Fence posts are sold in standard lengths, but the length you need to buy is always longer than the visible fence height, since a portion of every post has to go underground for stability. A common rule of thumb buries about a third of the post's total length, meaning a 6-foot fence typically needs a post closer to 9 feet long, not 6 — a detail that catches people off guard when ordering.
Frequently Asked Questions
How much of a fence post should be buried underground?
A common rule of thumb is to bury one-third of the post's total length, though taller fences, sandy soil, or high-wind areas may need up to half the post buried for stability.
What length post do I need for a 6 foot fence?
Using the standard one-third burial rule, a 6-foot (72 in) fence needs roughly a 9-foot post, so most people round up to the nearest standard length sold, often 10 feet.