Fence Post Concrete Calculator
Calculate how many bags of concrete you need to set your fence posts.
The concrete around a fence post only needs to fill the space between the hole and the post itself — not the whole hole — since the post displaces its own volume. This calculator subtracts an approximate square post footprint from the round hole's cylinder volume for each post, then multiplies by how many posts you're setting to get a total bag count.
Frequently Asked Questions
How deep should a fence post hole be?
A common rule is to bury one-third to one-half of the post's total length, with a minimum of 24 inches for most residential fences, adjusted for local frost depth requirements.
How many bags of concrete per fence post?
A typical 10-inch-diameter, 2-foot-deep hole with a 4×4 post needs roughly one to two 50 lb bags of concrete — but always calculate based on your actual hole size, since diameter affects volume significantly.
Guidence
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