Fence Post Depth & Concrete Calculator
Post Depth & Concrete
Calculate ideal post depth and concrete per hole
Frost Line Depth Guide
Determine post depth based on frost line zone
Formula
Post Depth = max(Frost Line + 6", Fence Height / 2) | Concrete Volume = pi x r^2 x depth - post_area x depth
Frequently Asked Questions
How deep should a fence post be?
The general rule is to bury 1/3 to 1/2 of the total post length underground. For a 6-foot fence, use 8-foot posts buried 24-36 inches deep. In cold climates, posts must extend below the frost line (check local codes) to prevent frost heave.
How much concrete do I need per fence post?
A typical fence post in a 10-inch diameter hole, 24 inches deep, requires about 0.4 cubic feet of concrete, or roughly one 50-lb bag of fast-setting concrete. For deeper holes (36 inches), you will need 1.5 to 2 bags per post.
Should I use fast-setting or regular concrete for fence posts?
Fast-setting concrete (like Quikrete Fast-Setting) is ideal for fence posts. You can pour it dry into the hole and add water on top. It sets in 20-40 minutes. Regular concrete requires mixing but may be cheaper for large projects.
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