Fence post calculator: how many posts do you need?

The short answer is one more post than panels for every uninterrupted span of fence. A span is a stretch of fence between two ends, two gate posts, or an end and a gate. Joined runs share a post only where their end points meet, and each span rounds up to whole panels first, because the calculator counts whole panels before any trimming.

This fence post calculator applies exactly that rule. Enter the run length, the gates and the panel width, and it lists each span, its panels and the posts it needs, then totals them. Posts are spaced evenly across a span, never farther apart than one panel width.

Why the quick rule often fails

Many people divide the length by the panel width and add one. That works only for a run with no gates. The same 100 ft run shows how quickly it breaks down.

With two gates the quick rule gives 13 posts, but the three separate spans need 15. Each span rounds up on its own and adds its own end post, so the quick rule undercounts by 2. Under-ordering posts is the expensive way to find that out.

A gate needs a post on each side of its opening. In this calculator those are the end posts of the spans next to the gate, so they are already in the count and a gate does not add posts on top of the spans. That is why one 4-foot gate in a 100 ft run left the total at 14 posts, the same as the run with no gate: the longer single span became two shorter spans that each rounded up differently.

A corner is a shared post. When two runs meet at the same coordinate they use one post, which is how the corner example in the Fencekind studio, a 30-foot run joined to a 20-foot run with a 4-foot gate, comes to 9 posts rather than the 10 you would count by treating the runs separately.

What the post count leaves out

• Post sizes and depth. Gate, end and corner posts are often larger or set deeper than line posts; the count does not say which are which.
• Concrete, brackets, caps and fasteners.
• Slopes, obstacles and local requirements for spacing or footing depth.

How far apart should fence posts be?

In this calculator, posts are one panel width apart or slightly closer, because each span is divided into equal bays. Your panel manufacturer and local rules set the real limit, so confirm both.

Do I count the end posts separately?

No. The count already includes both ends of every span.

Can I use this for a fence with corners?

Calculate each straight run, then remember that runs meeting at a corner share one post, so subtract one for each shared corner. For a full layout, the estimating tool counts shared posts for you.

Want the method behind the numbers? Read how to calculate fence posts, or browse all fence guides.

Measuring a whole job with corners and several materials? The fence estimating software page shows how Fencekind turns a measured layout into an estimate, and the field guides cover the studio steps. This calculator is planning arithmetic, not a quote or a survey.