Fence Calculator

A 150 ft privacy fence: 20 posts, 57 rails, 344 pickets, 40 bags of concrete

Length, height, and post spacing become posts, rails, and pickets or boards, plus the concrete to set the posts — four rounding rules in sequence. The quickest way to read them is to watch one run go through: 150 ft of privacy fence, 6 ft tall, posts every 8 ft, no gates.

Posts come first, because the rail and concrete counts hang off them. ceil(150 ÷ 8) = 19 sections, plus one post to close the last, so 20 posts, each sized at 1.5 times the fence height — about 9 ft — so exactly a third sits below ground. Rails run between each pair at the default of 3 per section for a fence 6 ft or taller (2 below 6 ft): 3 × 19 = 57 rails. Pickets divide the run by board width plus gap, so 5.5 in boards butted with no gap, plus a 5% waste allowance for split or miscut stock, is about 344 pickets. Concrete is 2 bags per post plus 2 per gate: 20 × 2 = 40 bags.

Tighten spacing to 6 ft and the same run needs 26 posts, 25 sections of rail, and 52 bags of concrete — but the picket count does not move, because pickets follow the length of the run, not how many sections it is cut into. Spacing drives posts, rails, and concrete; board width and gap drive pickets.

A 6 ft fence buys a 9 ft post — and the frost line outranks the one-third rule

Post length is derived, not entered: 1.5 times the fence height, which puts exactly a third of the post underground. That is the one-third rule — bury at least a third of the total post length. A 6 ft fence takes roughly a 9 ft post with about 3 ft buried; a 4 ft fence takes a 6 ft post with 2 ft buried.

Two exceptions this page cannot see: frost-prone areas need holes below the local frost line whatever the rule returns, and sandy or loose soil usually needs extra depth on top of that. Check your local building code before buying post stock cut to the length shown.

Spacing is the other input that moves the post count, and 6 to 8 feet on center is the residential wood standard — 6 ft for taller fences, high-wind sites, or softer soil, 8 ft to match standard lumber lengths. Residential chain link runs looser, around 10 ft between line posts, with commercial jobs often tightening to 8 ft, which is why the chain-link line-post estimate carries its own spacing field.

Gap 0, gap 2 in, or board-on-board: 344 pickets becomes 447

One dimension decides the picket count — board width plus the gap beside it. A traditional picket fence uses a gap greater than 0, commonly 2 to 4 inches, so fewer boards cover the run. Set the gap to 0 and you have a butted privacy fence: boards touching, no sightline gaps, and the highest picket count for that width. Both styles run through the same arithmetic, so there is no separate setting to find.

Board-on-board breaks the pattern. It alternates boards on the front and back of the rails so every gap on one side is covered by a board on the other, holding full privacy from both directions even as the wood shrinks. It consumes roughly 30% more lumber than a single butted layer — a commonly cited rule of thumb applied as a multiplier rather than exact overlap geometry. On the run above that turns about 344 pickets into about 447.

The waste allowance sits on top of whichever style you pick. 5% is the default and covers boards that arrive split or cupped and cuts that go wrong; raise it for rough stock or a run full of angles.

150 ft costs $1,500-3,750 in chain link and $4,500-9,000 in vinyl

Materials & Cost prices a run by length rather than by piece, because that is how the three types are quoted. On 2026 US installed figures, chain link is the cheapest common type at about $10-25/ft, wood about $15-45/ft, and vinyl about $30-60/ft. Across the same 150 ft that is roughly $1,500-3,750 in chain link, $2,250-6,750 in wood, and $4,500-9,000 in vinyl — the type decides more of the budget than anything else here.

Wood splits by species: about $15-30/ft for pressure-treated pine, $25-45/ft for cedar. Privacy and picket cost the same per foot; board-on-board costs more for the extra lumber, not a different rate. Vinyl is sold as pre-assembled panels rather than pickets, so it is priced by length and stays out of the picket count, which is a wood figure.

Chain link is sized differently again: select it and the tool returns mesh area (length × height), rolls at your supplier’s roll length, and a line-post count at your chosen spacing, alongside the cost. Larger-diameter terminal posts belong at every corner and end, and are counted separately.

Switch the region to the UK and the unit becomes metres at £50-180/m

Choosing a region does two things at once: it switches the length unit to metres where that is standard — the UK and Australia — and pre-fills a regional starting cost per unit length for wood, vinyl, and chain link. UK garden fencing commonly runs roughly £50-180/m installed; Australian timber paling about A$70-105/m and chain link A$40-65/m; Canada keeps feet, at about CA$27-50/ft for wood and CA$38-65/ft for vinyl.

Pick “Other / custom” for anywhere else and enter your own rate. Every regional figure is a sourced 2026 starting point, not a quote. The post, rail, and picket formulas in the other mode carry no currency at all and work identically in feet or metres, in any country.

One gallon covers 150-300 sq ft, so staining both faces doubles the order

Turn on “Calculate stain needed” under Wood in Materials & Cost and the tool multiplies length × height × sides, then divides by the coverage you enter. Sides is 1 for a single face and 2 for both, and it is the largest lever in the calculation: a 150 ft fence 6 ft tall is 900 sq ft on one face and 1,800 sq ft on two.

Coverage is the second lever, wide enough to double the order on its own. One gallon typically covers 150-300 sq ft depending on the stain and how porous the wood is, so read the product label instead of accepting the 300 default: at 900 sq ft that is 3 gallons against 6.

The 20-post count assumes a straight, level, permit-free run

Every figure above comes from one straight run on level ground, and that is where its limitations begin. Slopes, corners, and obstacles — trees, utilities, a shed in the way — change the real counts, usually upward: each corner needs a post of its own, and each grade change has to be stepped or raked.

The calculator also does not check local fence-height limits, setback and boundary rules, or homeowners’-association requirements; confirm those before you build. It cannot judge soil conditions or frost depth beyond the one-third rule above, and it is not a substitute for a licensed contractor’s on-site quote. Cost, coverage, and roll-length figures are general starting points; local pricing, product specifics, and supplier packaging vary and change over time.

This is an independent calculator built by Calculator Matters, not affiliated with, endorsed by, or produced by The Home Depot, Lowe’s, Menards, B&Q, Bunnings, or any other retailer. It uses published fence-building formulas and general cost data, not one retailer’s catalog — and it is free in any browser, with no app, signup, or download.

Sources and methodology

The post, rail, picket, and concrete formulas follow commonly published fence-building rules of thumb, cross-checked against an independently published worked example. Regional cost figures are general, sourced 2026 starting points, not a live data feed.

• Homewyse — Fence Installation Cost (2026)

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