How to calculate fence materials
- Posts: divide the fence run (length minus gates) by the post spacing, round up for the number of sections, then add one post — plus one extra post for each gate.
- Rails: sections × rails per section. Fences up to about 5 ft usually have 2 rails; 6 ft privacy fences use 3.
- Pickets: fence length in inches ÷ (picket width + gap). A shadowbox or board-on-board style uses roughly 50% more.
- Concrete: most wood posts take one to two 50 lb bags of fast-setting concrete each.
Post spacing and depth
| Fence type | Typical spacing |
|---|---|
| Wood privacy fence | 6–8 ft (1.8–2.4 m) |
| Picket fence | 6–8 ft |
| Chain link | Up to 10 ft (3 m) |
| Vinyl panels | Panel width, usually 6 or 8 ft |
A common rule is to bury one third of the post (at least 2 ft for most fences) and go below the frost line in cold climates. A 6 ft fence typically uses 8 ft posts.
Before you build
- Call 811 (in the US) a few days before digging so underground utilities can be marked.
- Check property lines, HOA rules and local permits — many areas limit height to 4 ft in front yards and 6 ft in back.
- Use pressure-treated or rot-resistant posts rated for ground contact.
For post-hole concrete in other sizes, use the concrete calculator (round column mode).
Frequently asked questions
How many fence posts do I need for 100 feet?
With 8 ft spacing, 13 sections and 14 posts — plus one more for each gate.
How far apart should fence posts be?
Usually 6 to 8 feet for wood fences and up to 10 feet for chain link.
How many pickets are in 8 feet of fence?
About 17–18 pickets that are 5.5 inches wide with no gap.
How much concrete per fence post?
Usually one to two 50 lb bags per post, depending on hole size.