How deep should you sink posts for a fence?

For a fence, posts should generally be sunk at least one-third of their above-ground height into the ground, with a minimum depth of 24 to 36 inches for stability. In areas with frost, it's advisable to set the posts below the frost line, which can vary by region. Additionally, using concrete or gravel for support can enhance stability and longevity. Always check local building codes for specific requirements.