Fence Calculator
Estimate fence posts, sections and pickets needed.
Center-to-center distance between posts.
Results update as you type.
How it works
A fence calculator estimates the main materials a straight fence run needs — posts, sections and pickets — from just the total length and the spacing you want between posts. It divides the length by the post spacing to count the sections, or panels, then adds one post because a fence always needs a post at both ends in addition to the ones between panels. This plus-one is the classic fencepost problem: five sections in a row are held up by six posts, not five. Pickets are estimated from the length assuming each board is about six inches wide and butted against its neighbors, so the tool divides the length by half a foot. Getting these counts right matters because posts are the costly, labor-heavy part of a fence — each one means digging, setting and often concreting — so knowing the number up front drives both the budget and the day's work. This is a planning estimate for a straight run with evenly spaced posts; corners, gates and changes in direction each add a post, and sloped ground needs extra allowance, so add a small margin. It also assumes solid, butted pickets — a spaced picket or shadowbox style changes the board count. Homeowners, fencers and landscapers use it to price a project and order posts, rails and boards before breaking ground. The divide-and-add-one method is standard practice for anything spaced evenly along a line.
Sections = ⌈fence length ÷ post spacing⌉; posts = sections + 1; pickets = ⌈fence length ÷ 0.5⌉
Dividing the fence length by the post spacing and rounding up gives the number of sections, or panels, between posts, since a partial run still needs its own section. The post count is the section count plus one, because a fence with several sections needs a post at both ends as well as between every pair of sections — the fencepost principle. Pickets are counted by dividing the fence length in feet by 0.5, treating each picket as roughly six inches wide, and rounding up. This picket figure assumes boards butted edge to edge; a spaced or shadowbox layout would change the count.
Source:Standard construction estimation (linear layout method)
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter fence length.
- 2
Adjust the options
Adjust post spacing if they apply — sensible defaults are already set.
- 3
Read your result
Posts needed updates instantly as you type — no button to press.
Frequently asked questions
How far apart should fence posts be?
Six to eight feet on center is the usual range for most wood and vinyl fences, with eight feet common because it suits standard rail lengths. Closer spacing makes a stronger, stiffer fence and suits tall or windy sites, while wider spacing uses fewer posts but flexes more. Heavier fences and gate openings need posts closer together or beefier posts. Enter your intended spacing and the calculator counts the posts and sections to match.
Why is there one more post than sections?
Because posts sit at the ends of sections, not in the middle. A single section needs a post at each end — two posts for one panel. Add another section and you add one post, not two, since the middle post is shared. So the post count is always the number of sections plus one. This fencepost principle is easy to forget and is exactly why counting sections alone leaves you one post short.
How many pickets do I need?
It depends on picket width and whether they are butted tight or spaced apart. This calculator assumes six-inch pickets set edge to edge, so it divides the fence length by half a foot. Narrower pickets or a gap between them changes the count — a spaced or shadowbox layout uses fewer or more boards respectively. Enter your real picket width by adjusting for it, and always add a few spares for splits and culls.
Does this account for corners and gates?
No. This is a straight-run estimate, and every corner or change in direction adds a post, while each gate needs a sturdier post on each side and reduces the picket run. Add one post per corner and plan gate posts separately, since they carry the swinging weight and often need to be larger and set deeper. Treat the result as a baseline and add these fittings for your specific layout.
How much extra fencing material should I buy?
Add a small margin, around 5 to 10 percent on pickets and rails, to cover splits, warped boards and cutting waste, plus spare posts for corners and gates the straight-run formula does not count. Sloped or uneven ground also consumes a little more material as panels are stepped or raked. Buying a few spares up front avoids a mid-project trip and lets you match lumber from the same batch later.