Fence Post Calculator
Determine **how many fence posts** you need with recommended hole depth and spacing. **Fence post calculator** solving the classic fencepost problem.
Formula & Explanation
This calculator solves the classic "fencepost problem" in fence construction. For a straight fence run: Posts needed = ceil(fence_length ÷ post_spacing) + 1 The "+1" accounts for the final post at the end. For example: - 100 ft fence at 8 ft spacing = ceil(100/8) + 1 = 14 posts Sections = ceil(fence_length ÷ post_spacing) [spaces between posts] Recommended hole depth follows the 1/3 rule: hole_depth ≈ above_ground_height ÷ 3, with a minimum of 2 feet and respect for local frost line depth.
Assumptions
- •Posts are placed at the beginning and end of the fence line
- •Straight run (no corners or gates-adjust as needed)
- •Post spacing is measured from center to center
- •Recommended depth is 1/3 of above-ground height; frost line and local code take precedence
- •Frost line depth varies by geography (0-4 feet); always verify with local building department
- •Does not account for slopes or uneven ground
Example Calculation
A 100-foot fence with 8-foot post spacing requires 14 posts (the fencepost problem). This creates 13 sections (spaces between posts). For a 6-foot tall post, the recommended hole depth is 2 feet (1/3 of height, meeting the frost line minimum). The actual spacing may vary slightly to fit the total length evenly.
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