Fence Posts Calculator

Fence materials come from one division and a few additions. The post count is the length divided by the spacing plus one, and everything else follows from the number of sections.

Fence lengthThe total run of the fence line, in feet.Post spacingCentre to centre distance between posts, in feet. Eight is the common standard.Rails per sectionHorizontal rails between each pair of posts. Use three for a six foot fence.Picket widthThe face width of one picket, in inches.Gap between picketsThe space left between pickets, in inches. Use zero for a solid board fence.Concrete bags per post60 pound bags of concrete per post. Use more for corners and soft ground.

Posts

Sections: 15
Rails: 30
Pickets: 263
Concrete bags: 32

Values update as you type. This calculator covers the single scenario its formula assumes — see Common Mistakes for what it leaves out.

The formula this calculator uses

posts = fence length / post spacing + 1, rounded up

posts: The number of posts including both ends
sections: The number of gaps between posts
rails: Horizontal members, usually two or three per section
pickets: Vertical boards, counted from their width plus gap

How to check the result by hand

1
Divide the run by the spacing
A 120 foot fence with 8 foot spacing gives exactly 15 sections. If the division is not whole, round up because a partial section still needs two posts.
2
Add one for the end post
Fifteen sections have sixteen posts. Mark the corners and gate openings on this count before ordering anything.
3
Count the rails
Fifteen sections at two rails each is 30 rails. Use three per section for a six foot privacy fence, which would be 45.
4
Count the pickets
The run is 1440 inches and each picket with its gap takes 5.5 inches, so 262 pickets fit and one more closes the last gap, giving 263. Two bags of concrete per post means 32 bags.

For worked examples, common mistakes and the limits of this formula, read the full How To Calculate Fence Posts page.