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How to plan a wood fence: posts, rails and pickets

A wood fence is three parts repeated along a line: posts, rails and pickets. Once you know the length and the spacing, the counts follow from simple arithmetic. This guide shows the method and the choices that move the numbers.

Updated By Matholio Editorial Team3 min read

The short answer

Divide the fence length by the post spacing and round up to get the sections. Posts are one more than the sections, rails are the sections times the rails per section, and pickets are the length in inches divided by the picket width plus any gap. A 100 ft fence at 8 ft spacing with 3 rails and solid 5.5 in pickets needs 14 posts, 39 rails and 219 pickets.

Step 1: Lay out the line

Measure the full length along the line where the fence will stand. Include the gap for any gate, and treat gate posts as extra. Check local rules first: Home Depot notes you will likely need a permit and that backyard fence height is often limited, commonly to 6 or 8 feet.

Step 2: Space the posts

Hoover Fence says most wood fences use posts 8 ft apart, measured center to center, because lumber is sold in 8 and 16 ft lengths, and that wider spacing tends to make rails sag. Angi and Home Depot give a range of 6 to 8 ft. Closer spacing makes a stiffer fence and suits windy sites or heavy privacy panels.

Sections = fence length ÷ post spacing, rounded up

Posts = sections + 1

Every section needs a post at both ends, which is why the count is one more than the sections. Corners and gates need extra care and often extra posts.

Step 3: Count the rails

Rails are the horizontal 2 × 4s that the pickets attach to. Fences up to about 4 ft tall usually take 2 rails per section, and taller privacy fences take 3. Rails = sections × rails per section.

Step 4: Count the pickets

Convert the fence length to inches and divide by the width of one picket plus the gap between pickets. A nominal 1 × 6 picket is about 5.5 in wide. Home Depot gives the same method: 120 ft is 1,440 in, and dividing by the picket-plus-gap width gives the count.

Pickets = fence length × 12 ÷ (picket width + gap), rounded up

Worked example: 100 ft of fence

  1. Sections at 8 ft: 100 ÷ 8 = 12.5, rounded up to 13.
  2. Posts: 13 + 1 = 14.
  3. Rails with 3 per section: 13 × 3 = 39.
  4. Pickets, solid with 5.5 in boards: 1,200 ÷ 5.5 = 218.2, rounded up to 219.
Wood fence counts for common runs (8 ft spacing, 3 rails, 5.5 in pickets unless noted)
Fence Posts Rails Pickets
50 ft 8 21 110
100 ft 14 39 219
150 ft 20 57 328
100 ft at 6 ft post spacing 18 51 219
100 ft with a 2.5 in gap between pickets 14 39 150
60 ft, 2 rails per section 9 16 131

What changes the numbers most

  • Post spacing: moving from 8 ft to 6 ft on a 100 ft fence raises posts from 14 to 18 and rails from 39 to 51, while pickets stay the same.
  • Picket gap: a solid privacy fence uses 219 pickets per 100 ft, and a 2.5 in gap cuts that to 150.
  • Rail count: dropping from 3 rails to 2 saves a third of the rails on shorter fences.

What is not in the count

  • Gates, gate hardware and extra posts for gates and corners.
  • Concrete or gravel for the post holes. Post holes are commonly dug at least 2 ft deep.
  • Screws or nails, post caps and wood preservative.
  • Waste for damaged or warped boards. Buy a few extra pickets.

Use the concrete calculator to size the footing for each post.

Common mistakes

  • Counting posts as equal to sections instead of one more.
  • Forgetting the gate opening and its extra posts.
  • Using the nominal 6 in picket width instead of the real 5.5 in.
  • Skipping the permit and property-line check.

Calculators for this job

These calculators do the arithmetic from this guide. Each card shows the result for a typical project; open one to enter your own measurements.

Fence Calculator 100 ft privacy fence 14 posts Open calculator Concrete Calculator 10 × 10 ft slab, 4 in thick 1.36 cubic yards Open calculator

Frequently asked questions

How far apart should fence posts be?

Hoover Fence says most wood fences use 8 ft on centers. Angi and Home Depot give a range of 6 to 8 ft, with closer spacing for taller or more exposed fences.

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

At 8 ft spacing a 100 ft fence has 13 sections and needs 14 posts. At 6 ft spacing it has 17 sections and needs 18 posts.

How many fence pickets do I need per foot?

With solid 5.5 in pickets you need about 2.2 per foot, so 219 for 100 ft. With a 2.5 in gap it is 1.5 per foot, or 150 for 100 ft.

How many rails does a fence need?

Plan 2 rails per section for fences up to about 4 ft tall and 3 rails for taller privacy fences.

Sources

  1. Hoover Fence, Wood Fence Calculator
  2. The Home Depot, How to Build a Fence
  3. Angi, How to Build a Wood Privacy Fence in 8 Steps
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