The short answer
For one straight run with no gates, divide the length by the panel width, round up to whole panels, and add one. A 100 ft run with 8-foot panels is 12.5 panels, rounded up to 13, plus one post: 14 posts.
Everything else is a refinement of that one rule: gates split a run into separate spans, each span rounds on its own, and posts shared at corners are counted once.
How to count posts, step by step
- Break the fence into spans. A span is a stretch of fence between two ends or gate openings. A gate in the middle of a run makes two spans.
- Count panels in each span. Divide the span length by the panel width and round up to a whole panel.
- Add one post per span. Posts at every panel boundary, including both ends, means panels plus one.
- Add the spans together. That is the total if no two runs meet.
- Subtract shared corner posts. When two runs meet at the same corner they use one post, so remove one for every shared corner.
Example 1: one 100-foot run, with and without gates
The same 100 ft run, 8-foot panels, and 4-foot gates spaced evenly along it. Each row counts spans as (panels) in each span.
| No gate | 13 panels → 14 posts |
|---|---|
| One 4 ft gate | 48 ft (6) + 48 ft (6) → 12 panels, 14 posts |
| Two 4 ft gates | 23 ft (3) + 46 ft (6) + 23 ft (3) → 12 panels, 15 posts |
The quick formula on the two-gate run would give 92 ft ÷ 8 ft, rounded up, plus 1 = 13 posts. The span method gives 15. The difference comes from rounding each span separately and from every span having its own end posts, which is how a post count can come up short at the supplier.
Example 2: a closed yard with shared corners
An 80 ft by 60 ft yard fenced on all four sides, with 8-foot panels and no gates. Each long side is 10 panels and needs 11 posts. Each short side is 60 ft ÷ 8 ft = 7.5, so 8 panels and 9 posts.
| Two long sides | 2 × 11 = 22 posts |
|---|---|
| Two short sides | 2 × 9 = 18 posts |
| Shared corner posts | − 4 |
| Total posts | 36 |
| Total panels | 36 |
The four corner posts are each counted by two sides, so they come out once. With 6-foot panels the same yard needs 48 panels and 48 posts, because each side rounds up to its own whole number of panels.
What changes the count
- Panel width. The same 100 ft run takes 18 posts with 6-foot panels instead of 14 with 8-foot panels.
- Gates. Each gate adds a span boundary. See how gate openings change fence footage.
- Corners. Every shared corner removes one post from the sum of the sides.
- Where the posts are spaced. In these examples posts are spaced evenly within a span, never farther apart than one panel width.
What a post count does not tell you
The count says how many posts, not which kind. Corner, end and gate posts are often larger or set deeper than line posts, and your product and local rules decide the sizes. The count also leaves out concrete, post caps, brackets and fasteners, slopes, obstacles, and any extra posts for bracing. Check spacing and footing requirements with your local building office before you buy.
Assumptions used on this page
- Level, straight runs measured in feet; 8-foot panels unless a different width is stated.
- Posts at every panel boundary, one panel width apart or closer.
- No waste or spare allowance. Add that yourself if you buy spares.
- All examples are fictional and are calculated with the same planner as the fence post calculator.
Questions
How many posts do I need for 100 feet of fence?
With 8-foot panels and no gates, 14 posts. With 6-foot panels, 18. Gates change it, as the example above shows.
How far apart should fence posts be?
That depends on the fence product and local rules. The counts here assume posts one panel width apart or slightly closer, because each span is divided into equal bays.
Do gates need extra posts?
In this method the posts beside a gate are the end posts of the neighbouring spans, so they are already counted. Gate hardware and any heavier gate posts are separate items.
Where do I go from here?
Measure the yard in runs with how to measure a yard for a fence, then work out panels with how many fence panels you need. Contractors can see the whole estimate on the fence estimating software page.