Why is a 1×6 not six inches wide?

It is milled to six inches rough, then dried and planed smooth, which takes it down to 5.5 in. The nominal name stuck. The same is true up the range: a 2×4 is 1.5 × 3.5 in.

Should I leave a gap between pickets?

A small one, usually about a quarter inch. Pressure-treated wood arrives wet and shrinks as it dries; boards butted tight can cup or push each other out of line. Leaving no gap is a choice, not a default.

How much waste should I allow?

Ten percent is typical for cut-to-fit stock. It covers the boards you cut short, the ones with a bad knot in the wrong place, and the last section that does not land on a full board.

Fence Ledger

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

One hundred feet of privacy fence takes a specific number of pickets, and the most common way to get it wrong is to use the size printed on the label.

Pickets needed

230

209 to cover the run, plus a 10% waste allowance.

What the usual answer misses

A board sold as a "1×6" picket is actually 5.5 inches wide. Working from 6 inches undercounts by about 9% — nine pickets short on a hundred-foot fence, discovered when you run out with two sections left to go. The gap between boards matters just as much: a quarter-inch gap over a hundred feet is another four pickets.

Work out your own

Every assumption above is editable. Change the length, the spacing, the hole size — the numbers and the working update as you go.

Units

Shape

Fence length

Height

Gates

Advanced options

These are typical values, not requirements. Post depth in particular is governed by your local frost line and building code — check before you dig.

Post spacing

Gate width

Picket gap

Hole diameter

Hole depth

Gravel base

Bag yield

Waste allowance

Posts

Sections

Pickets

230

Concrete

24 bags

Estimated cost

Materials only (DIY)

$800 – $2,000

Professionally installed

$2,500 – $5,500

National planning ranges compiled from published US construction cost guides, last checked September 2026 (confidence: medium-low). Prices vary sharply by region, season and contractor. These are estimates for planning, not quotes.

Sources: homeguide.com, calcsummit.com, ergeon.com, homewyse.com

Shopping list

Bill of materials for this fence
Material	Size	Quantity
Posts	4x4	14
Rails incl. waste	2x4	43
Pickets incl. waste	1x6	230
Concrete mix		24bags
Gravel		6bags
Exterior screws		≈1,500

Why these numbers

How we got the section count

Run 1: 100 ft ÷ 8 ft = 12.5, rounded up to 13 sections

How we got the post count

2 posts are fixed by the shape itself
2 at the open ends
12 line posts spaced between them
14 posts in total

How we got the picket count

Each picket covers 5.5 in plus a 0.25 in gap, so they repeat every 5.75 in
100 ft of fence needs 209 pickets
Plus 10% for offcuts, rounded up to 230

How we got the concrete

Each 10 in hole is 30 in deep, less 4 in of gravel base, leaving 26 in of concrete
The 4x4 post itself takes up part of that, so each hole needs the remainder
Across 14 posts
Divided by the 0.6 cu ft a bag yields: 23.27, so buy 24 bags

Common questions

Why is a 1×6 not six inches wide?: It is milled to six inches rough, then dried and planed smooth, which takes it down to 5.5 in. The nominal name stuck. The same is true up the range: a 2×4 is 1.5 × 3.5 in.
Should I leave a gap between pickets?: A small one, usually about a quarter inch. Pressure-treated wood arrives wet and shrinks as it dries; boards butted tight can cup or push each other out of line. Leaving no gap is a choice, not a default.
How much waste should I allow?: Ten percent is typical for cut-to-fit stock. It covers the boards you cut short, the ones with a bad knot in the wrong place, and the last section that does not land on a full board.