Fence Post Spacing Calculator
| Run | 8-ft spacing | 6-ft spacing | Concrete bags |
|---|---|---|---|
| 50 ft | 8 posts | 10 posts | ~10-18 |
| 100 ft | 14 posts | 18 posts | ~16-28 |
| 200 ft | 26 posts | 34 posts | ~30-54 |
Fence post spacing is run length divided by spacing, plus one for the post that ends the run - a 100-foot fence at 8-foot spacing wants 14 posts, not 12.5, because the division always rounds up and the last panel eats the remainder.
Bottom line: wood fence posts sit 6 to 8 feet apart, chain-link stretches to 10, and wind-exposed runs tighten every spacing by a foot - while the corners and gates are where the concrete doubles, because every direction the fence pulls is a direction the corner post has to hold.
The honest part: the panels are the secret constraint - pre-built wood panels come in 6 and 8-foot widths, and the run divides by the panel, not the post, which is why the pro lays out from the corners inward and cuts the last panel rather than spacing every post to fit the math.
How to use
- Enter the total fence run and your spacing - 8 feet is the wood standard, 6 in wind or for heavy panels - and read the post count.
- Add corner posts at every direction change and a post at each gate side; the calculator counts the straight run, and the corners are line items of concrete.
- Lay out from the corners inward: set the end posts first, stretch a string, and cut the last panel to fit rather than shrinking every spacing by an inch.
Frequently asked questions
How far apart should fence posts be?
Six to eight feet for wood privacy fence, up to 10 for chain-link, and tighter - 5 to 6 feet - for anything a strong wind loads up. The spacing that the panels come in decides the rest: 8-foot panels want posts at 8 feet with the panel hardware centered, and the run divided by the panel width is the layout that avoids the odd cut.
How many fence posts do I need for 100 feet?
Fourteen posts at 8-foot spacing - the run divided by the spacing rounds up and adds one for the end: 100 divided by 8 is 12.5, round to 13 spaces, plus the closing post. Corners, gates and direction changes add posts and each one wants its own concrete pour, which is why the corner count doubles the cement order.
How deep should fence posts be set?
A third of the above-ground height, with 2 feet as the working floor and below the frost line for anything that winters - a 6-foot fence wants posts 2 to 3 feet deep in concrete. The gravel at the bottom of the hole is drainage, not filler, and the post that rots at grade is the post set without the crown that sheds water away.
Why do my fence posts lean after a year?
The concrete was mixed too wet, the hole was too wide, or the post was set without a crown - wet concrete is weaker concrete, a bell-shaped hole holds frost heave like an anchor, and the water that pools at grade rots the wood at its weakest inch. Dry-set tamped concrete or a properly crowned wet pour both outlast the rushed version.