Fence post calculator
Calculate line posts, corner posts and end posts from run length and spacing, with concrete for each post included in the take-off.
Fence calculator
Enter your specs. Every result updates live and shows its formula.
Overview
This calculator counts the posts themselves: line posts set by your spacing, corner posts wherever the run changes direction, and an end post for a segment that has no corner to terminate against. Concrete for setting every post is rolled into the same take-off.
Not every fence shares one post spacing. Wood privacy commonly runs 8 feet and this calculator defaults to it, but chain link typically runs 10 feet, so the spacing control stays fully editable regardless of material choice.
Common mistakes
- Forgetting corner posts and end posts, which add to the total beyond the pure spacing math.
- Using one post spacing for every material, when chain link and some panel systems are designed for wider spacing than wood.
- Rounding the post count down on a run that does not divide evenly, which leaves a wobbly span at the end.
Related calculators
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- Privacy fence calculator Calculate posts, rails and pickets for a solid privacy fence in any material, with a zero-gap board layout by default.
- Wood fence calculator Calculate posts, rails, pickets and concrete for a pressure-treated pine, cedar or redwood fence. Every formula shown, cost optional.
Related reading
In-depth guides
Frequently asked questions
How many posts do I need for 100 feet of fence?
Divide the run by your spacing and add one for the end: at 8 foot spacing that is 13 posts for a straight 100 foot run (100 divided by 8 rounds up to 13), plus a corner or end post wherever a segment terminates without a corner.
What spacing should I use between posts?
8 feet is the common spacing for wood privacy and most board builds, and 10 feet is typical for chain link. The exact recommendation also depends on post size and material strength, so this calculator defaults to your material's norm and lets you change it.
Are corner posts counted separately from line posts?
Yes. A 90 degree corner uses a corner post sized and set to take tension from both directions, which is why this calculator counts corner and end posts on top of the line post spacing math.
What post size does a residential fence need?
A 4 by 4 post is the common minimum for wood privacy up to about 6 feet. Taller or panel-loaded runs often step up to 4 by 6 or 6 by 6, and chain link uses schedule-40 pipe sized to height and spacing; follow the manufacturer table for your load.
How many concrete bags does each post need?
It depends on the hole and the bag size. A common 10 inch by 24 inch hole with a 4 by 4 post takes roughly 2 to 3 bags of 60 lb mix with this calculator's volume math, which is why it reports 50, 60 and 80 lb counts together.
Should I set fence posts in concrete or gravel?
Concrete gives the most rigid setup and is the usual residential choice; gravel backfill drains better and can work in sandy or rocky ground where concrete would heave or crack. Use the post depth and setting guide for a full comparison.
How deep should a fence post be set?
A widely used rule is at least one third of the above-ground height, so a 6 foot post sets 24 inches or so, plus enough to stay below your local frost line. The depth calculator turns those two rules into one number per post.
Why does the calculator add concrete to the post count?
Because setting is part of the install cost. Your take-off is only honest when the bags per footer are in the same page as the posts themselves, which is exactly how this tool and the full fence calculator behave.