Fence Ledger

Fence Ledger

How much lumber do I need for a 100 ft privacy fence?

Three different pieces of timber go into a privacy fence and they are counted in three different ways, which is why a single number for lumber is never much use.

Boards to buy
230 pickets, 43 rails

Plus 14 posts. Picket and rail counts include a 10% waste allowance; posts do not, because you cannot buy a tenth of one.

What the usual answer misses

Posts, rails and pickets do not share a waste allowance. Pickets and rails get cut and some get rejected for warp, so a percentage on top is sensible. Posts do not — you buy them whole, you use them whole, and adding 10% to a post count just leaves you with a spare you did not plan for. Treating waste as one number across the whole order is how people end up over on one item and short on another.

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
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.

Posts
14
Sections
12
Pickets
222
Concrete
24 bags

Estimated cost

Materials only (DIY)
$1,000 – $2,600
Professionally installed
$2,700 – $6,100

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, angi.com, ergeon.com, homewyse.com

Shopping list

Bill of materials for this fence
MaterialSizeQuantity
Posts4x414
Rails incl. waste2x440
Pickets incl. waste1x6222
Concrete mix24bags
Gravel6bags
Exterior screws≈1,500
Walk gate kit1

Why these numbers

How we got the section count
  1. Run 1: 96 ft ÷ 8 ft = 12, rounded up to 12 sections
How we got the post count
  1. 3 posts are fixed by the shape itself
  2. 2 at the open ends
  3. 1 carrying a gate
  4. 11 line posts spaced between them
  5. 14 posts in total
How we got the picket count
  1. Each picket covers 5.5 in plus a 0.25 in gap, so they repeat every 5.75 in
  2. 96 ft of fence needs 201 pickets
  3. Plus 10% for offcuts, rounded up to 222
How we got the concrete
  1. Each 10 in hole is 30 in deep, less 4 in of gravel base, leaving 26 in of concrete
  2. The 4x4 post itself takes up part of that, so each hole needs the remainder
  3. Across 14 posts
  4. Divided by the 0.6 cu ft a bag yields: 23.27, so buy 24 bags

Common questions

What lengths should I order?
Rails in 8 ft lengths if you are spacing posts at 8 ft, so one rail spans one section with no joins. Posts have to cover the fence height plus everything below grade plus the gravel base, which usually means the next stock length up from what feels obvious.
Is it cheaper to buy panels instead?
Prefabricated panels save a great deal of labour and cost more per foot. They also assume even post spacing, so any run that does not divide neatly by the panel width needs a cut panel at the end, which is fiddly and wasteful. Board-by-board is more forgiving on an irregular boundary.
How much extra should I allow for a sloped yard?
More than on the flat, and how much more depends on the method. A stepped fence wastes little because the panels stay square. A racked fence needs each picket cut to its own length along the run, and the offcuts are rarely reusable.
Does pressure-treated timber need to season before staining?
Usually. Freshly treated timber holds a lot of moisture and most finishes will not take until it has dried, which can be weeks or months depending on the weather. Manufacturer instructions on the specific product are the thing to follow here.