How to calculate fence materials
Start with the number of sections — the fence length divided by your post spacing, rounded up. A straight run needs one more post than sections:
Sections = Length ÷ Post spacing • Posts = Sections + 1
A 100-foot fence with 8-foot spacing is 13 sections and 14 posts. Each section gets your chosen number of rails, so at three rails that's 13 × 3 = 39 rails.
Counting pickets
Pickets are based on the fence length in inches divided by each picket's width plus any gap:
Pickets = (Length × 12) ÷ (Picket width + gap)
A 100-foot fence is 1,200 inches; with 5.5-inch pickets butted tight, that's about 219 pickets. Add a gap for a spaced or shadowbox look and the count drops.
Don't forget
Add a post for each gate and corner, and plan on concrete to set every post — a concrete calculator helps size the bags. Gate hardware and the gates themselves are separate.
Frequently asked questions
How many fence posts do I need?
Divide the total fence length by the spacing between posts to get the number of sections, then add one for the final post. A 100-foot fence with posts every 8 feet needs 13 sections, so 14 posts. Corners and gates add posts.
How far apart should fence posts be?
Six to eight feet is typical for wood fences. Eight feet uses fewer posts and is common for panels, while six feet is sturdier for tall privacy fences or windy sites. Closer spacing means more posts but a stronger, less wobbly fence.
How many rails per section?
Two rails is standard for fences up to about 4 feet, and three rails for 6-foot privacy fences to keep the boards from warping. Taller fences may use four. The calculator multiplies your rails-per-section by the number of sections.
How many pickets do I need?
Convert the fence length to inches and divide by the picket width plus any gap between pickets. A 100-foot fence is 1,200 inches; with 5.5-inch pickets butted tight that is about 219 pickets. Add a gap to space them and the count drops.
Does this include gates and concrete?
No — it covers the straight fence line: posts, rails, and pickets. Add posts for each gate and corner, and plan on a bag or two of concrete per post to set them. Gate hardware and the gate itself are separate.
Disclaimer: Results assume a straight fence line and are estimates for planning. Add posts for gates and corners, and confirm spacing against local code and your panel or rail lengths.