Fence Calculator

Posts by the bay, pickets by the inch, gates taken out honestly

Enter each fence run on its own line and this calculator lays it out the way a builder does: each run divides into bays no wider than your post spacing, every bay brings its posts with it, and shared corners are subtracted once so they are not bought twice. Gate openings come out of the pickets and rails (a gate is a hole in the fence with hardware, not fence), pickets are counted across the real remaining length at their width plus gap, or overlapped for board-on-board, and the post-hole concrete is figured from the hole you actually dig. Prices are optional and itemised when given.

Fence runs (feet, corner to corner)

Disclaimer: This calculator gives estimates for general information only. It is not financial, medical or other professional advice. Check property lines, easements, utility locations, HOA and permit rules before digging; post depth follows frost and local practice.

What this calculator does

Fence materials fail in three classic places, and the layout here is built against each. Posts are undercounted when a fence is treated as one long line instead of bays between corners, so runs are entered separately and divided into bays at your maximum spacing, each run rounding its bay count up, because a 61 ft run at 8 ft spacing is eight bays, not seven and a wish. Corners are double-bought when runs share them, so shared corners are an explicit subtraction. And pickets are counted across gate openings that will never hold a picket, so gates leave the picket and rail maths entirely, while their posts stay in the count, since a gate hangs on posts like everything else, only harder.

How to use it

  • Measure corner to corner, post centres where you can. Each run is the straight between two corners or ends. Sloped ground: measure along the slope for stepped fences (the fence follows the hill), and see the limitations for racked panels.
  • Spacing is a stiffness decision. Eight feet is the economical standard for wood privacy fences; six feet resists wind and sag visibly better and costs its posts honestly in this count.
  • Picket coverage is width plus gap, or width minus overlap. A 5.5 in picket at a half-inch gap covers 6 in of fence; board-on-board at a 1 in overlap covers 4.5 in per board and buys privacy with the difference, which the count will show.
  • Concrete follows the hole, not the post. Diameter and depth are the digger’s numbers; a third of the post’s buried length and the frost line set the depth in cold country, and the bag yields used are printed with the results.

The layout conventions

  • Bays per run = run length / maximum spacing, rounded up. Posts = the sum over runs of (bays + 1), minus the shared corners you enter.
  • Picket length = total run length − (gates × gate width). Pickets = picket length in inches / coverage per picket, rounded up, then waste added and rounded up again.
  • Rails = picket length × rails per bay, bought as 8 ft boards, count rounded up.
  • Concrete per hole = π × (diameter/2)² × depth, converted to cubic feet; bags at the standard yields of about 0.45 cu ft per 60 lb bag and 0.60 per 80 lb bag, each rounded up on the total volume.

Worked examples

One 60 ft side fence. At 8 ft spacing the run makes 8 bays and 9 posts. One 4 ft gate leaves 56 ft to picket: at 5.5 in wide with a half-inch gap (6 in of coverage each), that is 672 / 6 = 112 pickets, or 124 with 10 percent waste. Two rails over 56 ft is 112 linear feet, 14 boards of 8 ft. Nine holes at 10 in diameter and 30 in deep hold 1.36 cu ft each, 12.27 cu ft in all: 28 bags of 60 lb or 21 of 80 lb, and the fence is fully shopped from six numbers.

The closed rectangle. Four runs of 60, 40, 60 and 40 ft total 200 ft of fence, but the posts do not total four independent runs: with 4 shared corners subtracted, the corner posts are bought once each, which on this layout saves exactly 4 posts against the naive sum. Corners are where fence estimates quietly inflate, and the subtraction field exists so the inflation is a decision, not a default.

Reading your results

Read posts against the layout drawing if you made one (and make one: a fence planned on paper argues with nobody at the lumber yard). Read the picket count with its waste already in as the order figure; the pre-waste count sits in the results too, only to show what the waste allowance is doing. Read concrete as the plan for unmixed bags; a hole that bellies out at the bottom in soft soil can drink a third more, which is the standard argument for two spare bags rather than a second trip.

Limitations

  • Slopes change everything politely. Stepped fences follow the conventions here with slope-measured runs; racked (contour-following) fences keep picket counts but the posts run longer, and steep sites deserve a layout sketch with heights per post.
  • Gate hardware and gate posts take real loads. Wide gates want larger posts, deeper holes and diagonal bracing; the count includes gate posts in the run total but does not upsize them, which is a builder’s call the results flag rather than make.
  • Bag yields are nominal. The 0.45 and 0.60 cu ft figures are the standard published yields for 60 and 80 lb bags; spilled, over-watered or belled holes all spend concrete the arithmetic cannot see.
  • Boundaries are legal facts, not measurements. The calculator trusts your run lengths. A fence on the wrong side of a line is a dispute with a materials list, and survey, easement and utility checks come before the first hole.

Frequently asked questions

How deep should fence posts go?

The working rule buries about a third of the post’s total length, with the hole bottom below the frost line where frost exists, because frost heave lifts shallow posts a fraction each winter until the fence line waves. A 6 ft fence on an 8 ft post buries 2 ft in mild country and 30 in or more where frost is serious, which is why depth is an input here rather than a baked-in number: the calculator takes your ground’s answer, and local practice (and any permit) outranks the rule of thumb.

Is 8 ft post spacing strong enough?

For a standard 6 ft wood privacy fence in ordinary wind exposure, 8 ft bays are the common build and perform adequately; the honest caveats are that rails sag sooner, pickets oil-can in high wind, and corners and gate posts carry loads the spacing does not describe. Six-foot spacing is the upgrade that shows in storms rather than in brochures. The calculator prices both truthfully, since spacing is your field to set, and comparing the two post counts is the real cost of the sturdier fence.

How many pickets do I need per foot?

Divide 12 by the coverage: a 5.5 in picket with a half-inch gap covers 6 in, so exactly 2 pickets per foot; the same picket butted tight needs 2.18 per foot, and board-on-board at a 1 in overlap needs 2.67 per foot. The per-foot view is a good sanity check on any quote, and the calculator’s per-run count is the same arithmetic carried honestly across gates and waste.

Should gates sit in their own bay?

Ideally a gate opening replaces a bay cleanly, with a post at each side of the opening taking the hinges and the latch; that is the layout the count assumes, with gate posts inside the run’s post total. A gate wider than the bay spacing, or one placed mid-bay for a path, adds posts the standard layout does not carry, and the practical fix is to split the run at the gate when you enter it, so the bays divide around the opening as they will on the ground.

Related calculators

Method: per-run bay layout at the entered spacing with shared corners subtracted once, gate openings removed from picket and rail lengths, pickets by coverage with waste, and post-hole concrete from the entered hole dimensions at standard bag yields. Last reviewed: 15 October 2026.