Fence Calculator
Calculate exact **fence materials** needed including posts, pickets, rails, and concrete. Comprehensive **fence calculator** for complete project planning with the fencepost problem solver.
Formula & Explanation
This calculator solves the classic "fencepost problem" to determine the exact number of posts needed. For a fence of length L with posts spaced S feet apart: posts = ceil(L ÷ S) + 1. Pickets are calculated by dividing total fence length by the sum of picket width and gap. Horizontal rails run the full fence length; total linear feet = fence length × rails per section. Concrete volume for each post hole is calculated as a cylinder (V = π r² h) minus the post volume. Total concrete = volume per hole × number of posts. One 80 lb bag yields approximately 0.6 cubic feet.
Assumptions
- •Post spacing is measured from center to center
- •Picket width is the actual width (not nominal; 1×6 board = 5.5" actual width)
- •Rails run continuously across all sections
- •Post hole depth should be about 1/3 of above-ground post height; frost line and local codes govern minimums
- •Post hole diameter is typically 3 times the post width for stability
- •Concrete calculation assumes round holes and square posts (subtracts post volume)
- •Does not account for gates, corners, or slope adjustments
Example Calculation
A 100-foot fence at 8-foot post spacing needs 14 posts. With 5.5-inch pickets and 1.5-inch gaps, approximately 154 pickets are needed. Two horizontal rails per section require 200 linear feet of rail material. Post holes require 1.24 cubic feet of concrete each, totaling 0.64 cubic yards or about 33 bags of concrete.
Inputs
Results
Common Fence Configurations
| length | spacing | posts | pickets | rails | concrete |
|---|---|---|---|---|---|
| 50 ft | 6 ft | 9 | 108 | 100 ft | 12 cuft |
| 100 ft | 8 ft | 14 | 154 | 200 ft | 18 cuft |
| 150 ft | 8 ft | 20 | 231 | 300 ft | 27 cuft |
Frequently Asked Questions
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