🪵 Fence Calculator for Posts, Panels, Rails and Pickets
By Shihab Mia · Updated 2026-07-14
This assumes a single straight run of fence on level ground. Posts are counted as the number of equal sections plus one for the closing end post, so a corner or a second straight run will add posts. The last section is allowed to be shorter than the spacing if the length does not divide evenly. Gates reuse the posts already counted, so each gate is subtracted from the panel total rather than adding posts. Buy a little extra material to allow for cuts, breakage, and terrain.
This fence calculator turns a straight run of fence into a clean material list: the number of posts, sections (panels), rails, and pickets you need. Enter the total length, your post spacing (8 ft is the usual default), and how many rails sit in each section, then subtract any gates. You get the totals instantly, so you can price the job before a trip to the lumber yard. The core rule it uses is simple. Divide the length by the spacing and round up to get sections, then add one post for the closing end, because a straight fence always needs one more post than it has gaps between posts.
What is the Fence Calculator?
A fence is built as a series of equal sections strung between posts, so almost every material total flows from two numbers you already know: the run length and the post spacing. The key relationship is that a straight run needs one more post than it has sections, because every section has a post at each end and neighbouring sections share the post in between. An 80 ft run at 8 ft spacing therefore has 10 sections and 11 posts. This fence calculator does that division for you, rounds the section count up so the fence always reaches the full length, and then derives panels, rails, and pickets from the section total.
The spacing you choose is a genuine trade-off, not just a default. Wider spacing uses fewer posts and less concrete, but it needs stronger rails and heavier panels to resist sagging and wind load. Most timber fences sit in the 6 to 8 ft range, chain-link can stretch toward 10 ft, and windy or sloped sites are usually pulled tighter to 6 ft. Because real runs rarely divide evenly into the spacing, the last section is often a little shorter than the rest. That is expected: you cut the final panel or rails to fit, or you nudge the spacing so the length divides cleanly, for example using 7 ft sections across an 84 ft run.
Rails are the horizontal members that the boards or pickets attach to. A common rule of thumb is one rail for every 24 inches of fence height, so a 4 ft fence uses 2 rails and a 6 ft fence uses 3. The rail total in this fence calculator is simply the number of panels multiplied by the rails per section. Pickets are the vertical boards that fill each section; how many you need depends on picket width and the gap you leave between them. A privacy fence butts pickets almost edge to edge, while a picket or spaced fence deliberately leaves a gap, which cuts the board count for the same run.
Gates are handled separately and are a common source of over-ordering. A gate takes the place of a panel but still hangs from posts that are already counted in the run, so each gate is subtracted from the panel total rather than adding posts. Wider or heavier gates sometimes call for beefier gate posts, but the count itself does not change. Corners and direction changes are different: each corner needs its own post, so if your boundary turns, add one post per corner on top of the straight-run result this tool gives.
Materials beyond the frame are worth planning at the same time. Each post typically needs concrete to set it, roughly two 50 lb bags for a standard hole about 10 inches wide and 24 inches deep, so multiply your post count to size the concrete order. You will also want fasteners, post caps, and gate hardware. Because wood splits, boards warp, and ground is rarely level, always buy a small surplus. Most builders add 5 to 10 percent extra on rails and pickets to cover cuts, knots, and breakage, which is cheaper than a second supply run mid-project.
Finally, use the fence calculator to compare options before you commit. Toggling spacing from 8 ft to 6 ft shows exactly how many extra posts, holes, and bags of concrete a stronger fence costs, and switching picket width or gap shows the swing in board count. Turning a boundary length into hard numbers this way is the fastest way to sanity-check a contractor quote or decide whether a material upgrade fits your budget.
When to use it
- Estimating posts, panels, rails, and pickets for a backyard timber, vinyl, or privacy fence before buying materials.
- Pricing a fencing job by turning a property boundary length into a clean material list and rough cost.
- Comparing post spacings (6 ft vs 8 ft) to see how post count, concrete, and cost change.
- Planning a run with one or more gates so you do not over-order panels.
- Sizing a concrete order by multiplying the post count by the bags each post hole needs.
- Sanity-checking a contractor quote against your own independent material count.
How to use the Fence Calculator
- Enter the total length of the fence run in feet.
- Set the post spacing (8 ft is a common default for timber fences, 6 ft for windy or sloped sites).
- Enter how many rails each section uses (2 for short fences, 3 for tall ones around 6 ft).
- Add the number of gates, if any, to subtract them from the panel count.
- Read off the posts, sections, panels, and rails, then add one post per corner for L-shaped runs.
Formula & method
Worked examples
A straight 80 ft fence at 8 ft post spacing, 3 rails per section, no gates.
- sections = round up (80 / 8) = 10
- posts = 10 + 1 = 11
- panels = 10 - 0 = 10
- rails = 10 x 3 = 30
Result: 11 posts, 10 sections, 10 panels, 30 rails
A 100 ft fence at 8 ft spacing, 3 rails per section, with 1 gate.
- sections = round up (100 / 8) = round up (12.5) = 13
- posts = 13 + 1 = 14
- panels = 13 - 1 gate = 12
- rails = 12 x 3 = 36
Result: 14 posts, 13 sections, 12 panels, 36 rails (last section is shorter than 8 ft)
Pickets for one 8 ft privacy section using 5.5 inch wide pickets butted with a 0.5 inch gap.
- section width = 8 ft = 96 inches
- per picket coverage = 5.5 + 0.5 = 6 inches
- pickets = round up (96 / 6) = 16 per section
- for a 10-section fence, pickets = 16 x 10 = 160
Result: About 16 pickets per 8 ft section, or 160 pickets for a 10-section run
Posts and sections for a straight run at 8 ft post spacing
| Fence length | Sections | Posts |
|---|---|---|
| 24 ft | 3 | 4 |
| 40 ft | 5 | 6 |
| 80 ft | 10 | 11 |
| 100 ft | 13 | 14 |
| 160 ft | 20 | 21 |
Common post spacing guidance by fence type
| Spacing | Typical use |
|---|---|
| 6 ft | Heavier panels, windy sites, sloped ground, or stronger support |
| 8 ft | Standard for most timber, privacy, and vinyl fences |
| 10 ft | Chain-link and light rail fences (check the maker maximum span) |
Rails and rough material cost by fence type (guide only, verify local prices)
| Fence type | Rails at 6 ft high | Typical material cost per linear ft |
|---|---|---|
| Chain-link | No rails (top rail only) | 8 to 18 USD |
| Wood / timber | 3 rails | 15 to 35 USD |
| Vinyl | 2 to 3 rails | 25 to 45 USD |
Common mistakes to avoid
- Forgetting the extra end post. A straight run always needs one more post than it has sections, because both ends need a post. Counting one post per section leaves you a post short at the end of the line.
- Ignoring corners and direction changes. This tool counts a single straight run. Each corner or change of direction usually needs its own post, so add one post per corner on top of the result.
- Assuming gates add posts. A gate hangs from posts that are already in the run, so it does not add posts. It does replace a panel, which is why gates are subtracted from the panel count here.
- Buying exactly the calculated amount. Wood splits, boards warp, and ground is rarely level, so order a small surplus of rails and pickets. Most builders add 5 to 10 percent extra for waste and offcuts.
- Forgetting concrete for the posts. Each post usually needs concrete to set it, often around two 50 lb bags for a standard hole. Multiply the post count by the bags per hole so the concrete order matches the fence.
- Using privacy picket counts for a spaced fence. Picket count depends on the gap you leave. A spaced picket fence needs far fewer boards than a privacy fence over the same run, so set the gap before you order pickets.
Glossary
- Post
- A vertical support driven or set into the ground that the rails and panels attach to.
- Section
- The span of fence between two neighbouring posts. The number of gaps in the run.
- Panel
- The pre-built or board-by-board infill that fills one section between posts.
- Rail
- A horizontal member running between posts that the boards or pickets fix to, usually 2 or 3 per section.
- Picket
- A vertical board fixed to the rails to form the visible face of the fence, commonly 3.5 to 5.5 inches wide.
- Post spacing
- The on-centre distance between posts, commonly 6 to 8 feet for timber fences.
- On centre
- A measurement taken from the middle of one post to the middle of the next, the standard way spacing is quoted.
- Gate post
- A post that carries a gate, sometimes set deeper or in more concrete because it bears swinging load.
Frequently asked questions
How many fence posts do I need?
Divide the total length by the post spacing and round up to get the number of sections, then add one for the end post. For example, an 80 ft run at 8 ft spacing has 10 sections and 11 posts. Add an extra post for every corner or change of direction.
How many fence panels do I need?
The number of panels equals the number of sections, which is the length divided by the spacing, rounded up. If your fence includes gates, subtract one panel for each gate, since a gate takes the place of a panel between two existing posts.
What is the standard spacing between fence posts?
8 feet on centre is the common default for timber, privacy, and vinyl fences, with 6 feet used for heavier panels, sloped ground, or windy sites, and up to 10 feet for chain-link. Always check the panel or rail manufacturer guidance, as some systems specify a maximum span.
How many rails does a fence need?
A common rule is one rail for every 24 inches of height, so a 4 ft fence uses 2 rails and a 6 ft fence uses 3 rails to stop the boards warping. This fence calculator multiplies the number of panels by the rails per section to give the total.
How many pickets do I need per section?
Divide the section width in inches by the picket width plus the gap, then round up. For an 8 ft (96 inch) privacy section with 5.5 inch pickets and a 0.5 inch gap, that is 96 / 6 = 16 pickets per section. A spaced picket fence with a wider gap needs fewer boards.
Does the calculator handle gates?
Yes. Enter the number of gates and each one is subtracted from the panel total, because a gate replaces a panel but hangs from posts that are already counted in the run. The post count itself does not change, though a heavy gate may call for a sturdier gate post.
What if my fence length does not divide evenly by the spacing?
The tool rounds the section count up so the fence covers the full length, which means the last section can be shorter than the others. You simply cut the final panel or rails to fit, or adjust the spacing so the length divides cleanly.
How much concrete does each fence post need?
A typical fence post hole about 10 inches wide and 24 inches deep takes roughly two 50 lb bags of concrete mix. Multiply that by your post count to size the order, and set gate and corner posts deeper for extra strength.
How much does a fence cost per linear foot?
As a rough material guide, chain-link runs about 8 to 18 USD per foot, wood about 15 to 35 USD, and vinyl about 25 to 45 USD, with professional installation often adding 10 to 30 USD per foot. Local prices vary, so treat these as a starting estimate and confirm with a supplier.
How do I calculate materials for a fence with corners?
Measure each straight run separately and calculate posts, panels, and rails for each, then add one shared corner post where two runs meet instead of counting an end post for both. Summing the runs this way avoids double-counting posts at the corners.