Post spacing is one number that moves three counts in different directions. Wider spacing cuts posts and rails, but pickets stay exactly where they were, because the fence is the same length.
Sections = fence length ÷ post spacing, rounded up
Posts = sections + 1
Rails = sections × rails per section
Pickets do not depend on post spacing
80 ft of fence at three spacings
These spacings are examples to show the effect on the count. They are not suggestions for what your fence should use.
| Post spacing | Posts | Rails (3 per section) | Pickets |
|---|---|---|---|
| 6 ft | 15 | 42 | 168 |
| 8 ft | 11 | 30 | 168 |
| 10 ft | 9 | 24 | 168 |
This example assumes
- One straight 80 ft run with no corners or gates
- 3 rails per section
- 5½ in pickets with ½ in gaps and 5% extra
From 6 ft to 10 ft spacing, posts fall from 15 to 9 and rails from 42 to 24, while the pickets hold at 168. A spacing that does not divide the run evenly rounds the section count up, and the planner treats that as the next whole section.
Why the spacing is not your call here
The right spacing for a real fence comes from the fence system, the panel or board design and local requirements. A product’s own instructions can mark posts at one distance and a different product another. Lowe’s instructions for one 4 × 8 picket panel, for example, mark posts 96 inches center to center. Follow your product’s instructions, enter that spacing in the planner, and read the counts.
This guide does not decide what spacing is structurally suitable, and nothing here replaces the instructions that came with your fence or a professional’s advice.
What changes the estimate?
- The spacing specified for your fence system
- The number of rails per section your system uses
- Corners, gates and ends, which a straight-run count does not include
- Whether the run divides evenly by the spacing, since a short last section still needs its own post
For the whole picket-fence count, see how many fence posts and pickets.