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Fence Calculator

Fence picket calculator

Calculate exactly how many pickets you need from your fence run, picket width and gap, including a waste factor.

Fence calculator

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Overview

Picket count comes from dividing the usable run, in inches, by the picket pitch: the board width plus whatever gap sits between boards. A privacy fence commonly runs a zero gap, a classic picket fence runs a visible gap like 1.75 inches, and board-on-board runs boards closer than their own width because they overlap.

Gate openings are subtracted from the run before the picket count is computed, so a gate does not silently inflate the picket total, and a waste factor is applied on top for cut ends and the occasional warped board.

Assumptions

  • Picket pitch is board width plus gap, with board-on-board handled as a smaller effective spacing because of the overlap.
  • Gate openings are removed from the run before counting.
  • A default waste factor of 10 percent is applied, editable in advanced settings.

Common mistakes

  • Computing pickets from the full fence length instead of the run after gate openings are subtracted.
  • Ignoring the gap between pickets on a classic picket-style fence, which changes the count meaningfully compared to a butted privacy fence.
  • Skipping a waste factor and running short by exactly the number of boards that get miscut or rejected.

Fence calculation formulas

The same math the calculator runs, in plain terms. Nothing here is a black box.

  • Sections

    sections = max(ceil(effective run / post spacing), 1)

  • Post count

    posts = (sections + 1) along the run, minus named corner and end posts already placed, plus 2 gate posts per gate

  • Effective run

    effective run = total length - sum of gate widths

  • Rail count

    total rails = sections x rails per section

  • Picket count

    pickets = ceil(run in inches / (picket width + gap)); total = ceil(raw x (1 + waste %))

  • Board-on-board pitch

    pitch = picket width - 1 in overlap

  • Panel count

    full panels = floor(run / panel width); add 1 cut panel if the remainder is over 0.01 ft; total = ceil(raw x (1 + waste %))

  • Concrete volume

    per-hole = pi x (diameter / 2)^2 x depth; total = per-hole x posts; bags = ceil(total / bag yield)

  • Slope-adjusted run

    slope run = effective run / cos(atan(slope % / 100)); shown alongside, counts use the flat run

  • Cost

    materials = (posts x post price + rails x rail price + infill x unit price + 60 lb bags x bag price) x regional multiplier; labor = effective run x labor per ft x terrain multiplier x regional multiplier; installed total = materials + gate hardware + removal + permit + labor

Every number the calculator shows comes from these formulas applied to your inputs.

In-depth guides

Buying guide

Picket count comes from one formula: divide the usable run, in inches, by the picket pitch, the board width plus whatever gap sits between boards, then round up and add a waste allowance. A zero gap, as on a butted privacy fence, gives the highest count for a given board width; a visible gap, as on a classic picket fence, lowers it; and an overlapping layout tightens the pitch below the board's own width and raises it again. This calculator is the single-purpose version of that formula, useful for checking a lumber order against a quote or against the fuller wood fence calculator, which runs the same math alongside posts and rails.

Gate openings matter before the division happens, not after. This calculator subtracts any gate width from the run first, so a 4 foot walk gate does not silently inflate the picket total for a stretch of fence that is not covered in pickets at all. Skipping that step is one of the more common ways a hand calculation comes out high, and it gets worse on a run with more than one gate.

A waste factor sits on top of the pitch math, typically around 10 percent, to cover cut ends at corners and the occasional warped or split board rejected on site. A simple straight run with no corners can run a lower waste allowance; an irregular boundary with several turns usually warrants more. Once the picket count is settled, the fence rail calculator handles the horizontal backer boards the pickets attach to, and the fence post calculator covers the posts those rails span between, the other two legs of a complete wood fence take-off.

For a worked example at common board widths, how many pickets for 100 feet of fence walks through the arithmetic step by step. Once materials are counted, the fence cost calculator turns the picket, rail and post counts into a total using your own local prices, and the wood fence installation guide covers how pickets actually get attached to the rails once the count is in hand.

Board-on-board layouts use a different version of this same formula: instead of adding a gap, the overlap between boards is subtracted from the width, which produces a smaller effective pitch and a correspondingly higher picket count for the same run. That distinction matters when comparing a quote across styles, since a board-on-board estimate that uses the plain width-plus-gap formula instead of accounting for the overlap will come in short of what the job actually needs.

Board width itself is worth measuring rather than assuming, since nominal lumber sizes do not always match actual milled width, and a half-inch difference compounds meaningfully over a long run. A 1x6 board, nominally 6 inches, is commonly milled to about 5.5 inches actual width, and a 1x4 to about 3.5 inches; entering the real measured width rather than the nominal size is what keeps the picket count accurate against what actually gets delivered.

Corner posts affect picket layout even though they do not change the total count: the last picket before a corner post often needs a slightly narrower rip cut to land the pattern correctly, which is a layout detail rather than something that adds boards, but it does mean the final board on each section is rarely a full-width piece straight off the stack. Planning for that cut, rather than discovering it while standing at the corner with a full board in hand, is part of what separates a tidy finished run from one with visibly uneven end pickets.

It is also worth ordering slightly more boards than the bare computed total even after the waste factor is applied, since matching stain or paint on a single replacement board months or years later rarely comes out identical to the weathered boards around it. Keeping a small reserve bundle of the same batch, cut from the same run of lumber, is a common practice among installers for exactly that reason, separate from the waste allowance this calculator already includes for cutting losses during the original installation.

Picket thickness, not just width, is worth noting when ordering, since a nominal 1 inch board is commonly milled to about 3/4 inch actual thickness, and that thickness affects fastener length and the overall look of the fence face rather than the picket count itself. Two fences built to the same width and gap can still look different if one uses thicker stock, which is a design preference separate from the quantity this calculator returns.

Delivery logistics are also worth planning around picket count rather than leaving until the last step: a large order of 1x6 boards for a long run is heavy and bulky enough that many suppliers deliver by the pallet rather than as individual boards, and confirming pallet quantities against the computed picket count avoids ordering in an awkward in-between amount that leaves either a wasted partial pallet or a shortfall.

Frequently asked questions

How many pickets do I need for 100 feet of fence?

It depends on picket width and gap. At a common 5.5 inch board with no gap, 100 feet (1,200 inches) needs about 219 pickets before waste, and roughly 241 with a 10 percent waste factor. Enter your own width and gap in the calculator for an exact count.

Does the picket count change if I add a gate?

Yes. A gate opening is subtracted from the fence run before pickets are counted, since that stretch is not covered in pickets at all.

What is the formula for pickets per linear foot?

Convert the run to inches, divide by the pitch (board width plus gap), and round up, then add waste. Board-on-board subtracts the overlap from the pitch instead of adding a gap, which raises the count.

What board width should I use?

5.5 inches is a very common milled width, with 3.5 and 7.25 inches also standard depending on the board. Measure your actual board if you already have it; the calculator takes the width you enter.

Why is a waste factor included?

Boards get cut to fit ends, gates and corners, and occasionally arrive warped or split on site. A 10 percent default is a common starting allowance; adjust it down for a simple straight run or up for an irregular boundary.

Should I buy an extra row of pickets anyway?

Buying one extra bundle beyond your computed count is common for fence work because you cannot match stain or paint perfectly later if a board needs replacing. That is a purchase preference, separate from the count the calculator gives you.

How do I measure picket pitch in the yard?

Pitch is the center-to-center spacing, board width plus gap. On a privacy fence that is the board width; on a picket fence add the gap; on board-on-board subtract the overlap. Keeping one pitch for the whole run keeps gaps even.

Do shadowbox fences need the same picket count formula?

The per-side formula is the same width-plus-gap pitch, but shadowbox runs boards on both faces of the rail, so a fence that looks filled from both sides needs roughly twice the boards a single-sided line would. This calculator counts per side; multiply for a two-sided spec.