How Many Fence Posts for a 100 Foot Fence?
Quick Answer
A 100-foot fence needs 14 posts spaced 8 feet apart, or 18 posts spaced 6 feet apart. The formula is length divided by spacing, plus one post for the final end.
- 8-ft spacing: 14 posts
- 6-ft spacing: 18 posts
- Formula: (length ÷ spacing) + 1
- Wood privacy fences use 6–8 ft spacing; ranch rail up to 8 ft
Formula
Divide the total fence length by the spacing between posts, round up, then add 1 for the starting post. Closer spacing means a stronger, more rigid fence.
Step-by-Step Calculation
- 1
Fence length
100 linear feet
- 2
Sections at 8-ft spacing
100 ÷ 8 = 12.5 → 13 sections
- 3
Add end post
13 + 1 = 14 posts
- 4
At 6-ft spacing
(100 ÷ 6 = 16.7 → 17) + 1 = 18 posts
Fence Posts for 100 Feet by Spacing
| Post Spacing | Sections | Posts Needed | Best For |
|---|---|---|---|
| 6 feet | 17 | 18 | Tall / privacy fences |
| 7 feet | 15 | 16 | Standard wood fences |
| 8 feet | 13 | 14 | Rail / chain-link fences |
| 10 feet | 10 | 11 | Ranch / wire fences only |
Add extra posts at corners, gates, and grade changes. Gate posts should be heavier (6×6) and set deeper than line posts.
Frequently Asked Questions
How far apart should fence posts be?
Standard spacing is 6 to 8 feet on center. Use 6 feet for tall privacy fences that catch wind, and up to 8 feet for chain-link or rail fences. Never exceed the panel or rail length you are using.
How many bags of concrete per fence post?
A 4×4 post in a standard hole needs 1 to 2 bags of concrete. For an 18-post fence at 6-ft spacing, plan on 18 to 36 bags total, plus extra for heavier corner and gate posts.
How many rails for a 100-foot fence?
A 3-rail fence at 8-ft spacing needs about 39 rails (13 sections × 3). Most wood privacy fences use 2 to 3 rails per section, so count 26 to 39 rails for a 100-foot run.