Fence Post Calculator: 14 Posts for a 100 ft Fence

What does fence posts needed 14 mean?

It means thirteen fence sections need fourteen posts, because every section needs a post at each end and neighbouring sections share one. The half-section is the trap: 100 ft divided by 8 ft is 12.5 sections, and you cannot buy half a section — the last short section still needs its end post, so 12.5 rounds up to 13 sections and the post count is sections plus one. Buy fourteen posts and the run closes exactly; buy thirteen and the last section has no end post.

Output · formula · meaning

Three things to check before you trust the number

First, check the run is really one run: a gate splits it into two runs, and each run needs its own starting post, so a gated 100 ft fence needs 15 posts, not 14. Second, check the spacing against the panel width: panels come in fixed widths, and a spacing that does not match the panel means cutting every panel. Third, remember corner posts and end posts are often heavier timber than line posts — the count is the same, but the shopping list should mark which posts are which.

Worked example

100 ft fence, 8 ft spacing. Sections: 100 ÷ 8 = 12.5, rounded up to 13. Posts: 13 + 1 = 14. In practice that is twelve full 8 ft sections and one short 4 ft section at the end — the short section still gets its end post, which is why the count rounds up instead of down. If the same fence used 6 ft spacing instead, the sections would be 17 (100 ÷ 6 = 16.67, rounded up) and the posts 18: tighter spacing is a real cost, not a small one.

Every branch, checked

With a 120 ft fence instead of 100 ft, the sections rise to 15 and the posts to 16. With an 80 ft fence, the sections fall to 10 and the posts to 11. With 6 ft spacing, the sections rise to 17 and the posts to 18 — four more posts for the same fence. With 10 ft spacing, the sections fall to 10 and the posts to 11 — but 10 ft spans can sag under a heavy panel, so the saving has a limit.

The reverses, worked backwards

The length behind 14 posts is 100 ft: at 80 ft the need is 11 posts; at 120 ft it is 16 posts. The spacing behind 14 posts is 8 ft: at 6 ft the need is 18 posts; at 10 ft it is 11 posts. Each reverse moves one input and holds the other, so the step is exactly one fence length or one spacing step.

What the defaults assume

The defaults assume one straight 100 ft run with posts every 8 ft and no gate, corner or change of direction. They do not assume panels of a different width, a gate, or a corner: each gate or corner adds a post to the count, so split the fence at every gate and corner and run each section through the same maths.

Who uses this

• A homeowner fencing a garden: the 14-post figure is the timber list, before a single hole is dug.
• A contractor quoting a fence: sections plus one is the count the quote is built on, whatever the length.
• A DIYer comparing spacings: 6 ft spacing costs four extra posts on this run — the price of a stiffer fence, stated plainly.
• A neighbour splitting a boundary fence: fourteen posts split two ways is seven each, with the starting post shared in the count.

Accuracy & limitations

The arithmetic is exact for the inputs entered; the judgement is the run and the spacing. Real fences have gates, corners and slopes, and each of those adds posts or changes spacing — a run measured around a corner as one straight length will undercount. Ground matters too: soft ground may want deeper holes or closer posts, which this count does not cover. Treat 14 as the planning figure for one straight run, and add one post per gate and per corner.

Cite this calculator

Bright Side Kit, “Fence Post Calculator: 14 Posts for a 100 ft Fence”, https://brightoolbox.com/fence-post-calculator/, accessed 2 November 2026. Students and researchers: cite the calculator name, the page URL and the date you used it, and quote the defaults (100 ft fence, 8 ft spacing) so the 14-post result can be checked.

Frequently asked questions