Fence Calculator
Calculate the number of fence posts, rails, pickets, and panels needed for any fence length. Supports common picket and panel fence styles.
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How to use this calculator
Number of posts = fence length / post spacing, rounded up, plus one end post. Pickets = total fence length / (picket width + gap).
- 1
Enter the total fence perimeter length and post spacing.
- 2
For panel fencing, enter the panel width to get panel count.
- 3
For picket fencing, enter picket width and gap between pickets.
- 4
Enter number of gates and gate width to exclude them from the calculation.
Frequently asked questions
How does this tool count fence posts?
Posts = the net fence length ÷ spacing, rounded up, + 1 end post + 2 posts for every gate. The net length is the total length minus gates × gate width. With the default 30 m fence, one 1.2 m gate and 2.4 m spacing, 28.8 ÷ 2.4 = 12, so 12 + 1 + 2 = 15 posts.
What happens when I enter a panel width?
A panel width above zero switches the tool into panel mode. Panels = net length ÷ panel width, rounded up, and the post spacing used for the post count becomes the panel width, because posts have to sit at the joints between panels. The picket count is not shown in panel mode. Leave the panel width at 0 to get pickets instead.
How are pickets counted?
Pickets = net length ÷ (picket width + gap), rounded up. The default 90 mm picket with a 50 mm gap repeats every 140 mm, so a 28.8 m run needs 206 pickets. Enter both values in millimetres. The count is for one face of the fence, so a double-sided design needs more.
How is rail length calculated?
It is the net fence length multiplied by the number of rails, which for 28.8 m and two rails is 57.6 m. Buying stock lengths, overlaps at joints and offcuts are not included, so round up when you convert metres of rail into boards.
Does the tool handle corners, slopes or uneven sections?
No. It treats the fence as one straight, level run. Corners usually reshuffle the spacing, because each straight side rounds up separately. Calculate each side on its own and then subtract one post for every corner post you counted twice. On sloping ground, the distance along the slope is longer than the plan length, so measure along the line of the fence.
Why do gates add two posts?
The tool assumes each gate needs a hinge post and a latch post of its own, and adds them on top of the line posts. If a gate sits where a line post would have been, the count can be one or two posts higher than you need, so draw the run and check it.
What happens if the gates are longer than the fence?
The tool stops and asks you to reduce the gates or their width, because a net length of zero or less has no meaning.
Does it say how deep the posts go or how the fence should be built?
No. Post depth, footing size, height limits, boundary rules and wind loading depend on the fence, the soil and your local regulations. The page counts items for a layout you have already chosen, so ask a builder, supplier or your local authority about construction details.
Fence calculator — posts, pickets, panels and rail length
Counting posts from spacing
A run of fence needs one more post than it has spans, which is the idea behind the formula. The tool subtracts the gate openings from the total length, divides by your chosen spacing, rounds up so the last span is never short, then adds the extra end post. Each gate then adds two posts of its own. That is how a 30 m boundary with one 1.2 m gate and 2.4 m spacing ends up at 15 posts: 12 spans, one end post and two gate posts. The spacing you enter is a layout choice, not a recommendation from the tool.
Worked examples
The table lists four fixed layouts run through the calculator. The first uses the default picket fence with a gate, the second is a 20 m panel fence with 1.8 m panels, the third has two 1 m gates and tighter pickets, and the last is a deliberately impossible case where the gate is wider than the fence.
| Layout | Net length | Posts | Panels / pickets | Rail length |
|---|---|---|---|---|
| 30 m, 2.4 m spacing, 90 mm pickets + 50 mm gap, 2 rails, 1 gate of 1.2 m | 28.8 m | 15 | 206 pickets | 57.6 m |
| 20 m of 1.8 m panels, no gates, 2 rails | 20.0 m | 13 | 12 panels | 40.0 m |
| 15 m, 2.5 m spacing, 70 mm pickets + 30 mm gap, 3 rails, 2 gates of 1 m | 13.0 m | 11 | 130 pickets | 39.0 m |
| 1 m fence with one 1.2 m gate | invalid | error shown | none | none |
Panels versus pickets
Panel mode and picket mode answer different buying questions. With panels, each unit has a fixed width, so the count is simply the length divided by that width, rounded up: 20 m of 1.8 m panels is 11.1, hence 12 panels, and 13 posts to carry them. With pickets, the repeat distance is the picket width plus its gap. Narrow the gap from 50 mm to 30 mm and the picket count rises quickly, as the third table row shows with 130 pickets over 13 m. Because pickets and panels are alternatives in this tool, set the panel width back to 0 whenever you want picket numbers.
Rails, gates and what gets rounded
Rail length is a straight multiplication of net length by the number of rails, so three rails over 13 m is 39 m. The post and panel counts are rounded up to whole units, while rail length is shown to one decimal place in metres and is not rounded to stock lengths. The gate itself, its hinges, latches and any gate frame are outside the tool; it only removes the gate width from the run and reserves two posts.
Where to double-check
These are material quantities for a single straight, level run, not a fence design. Corners, slopes, differing heights and the height or boundary rules that apply where you live all change what you need, and the tool does not read any of them. Post depth, concrete footings and wind exposure are decisions for a competent builder, fence supplier or the local authority. Use the totals for budgeting and a shopping list, and confirm details before you dig.
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Results are estimates for informational purposes only and do not constitute professional financial, medical, legal, or technical advice. Read full disclaimer →