How Many Fence Posts and Panels Do I Need? Linear Foot Math Explained

Counting posts and panels for a fence sounds simple - it is not. The number depends on panel width, gate locations and how the corners line up. For a quick reference, a 100 ft fence with 8 ft pre-built panels needs 13 panels and 14 posts - plus one extra post per gate for the latch side. Here is how the math actually works and where DIYers go wrong.

How many fence panels for 100 linear feet?

Divide your fence length by the panel width and round up:

• 6 ft panels: 100 ft / 6 = 16.67 → 17 panels
• 8 ft panels: 100 ft / 8 = 12.5 → 13 panels

The last panel is almost always a partial - you cut it to fit the final gap. 8 ft panels are the dominant length at home improvement stores because they cover the most ground per panel and per post, which means a faster install and less concrete. 6 ft panels are common in pre-built decorative styles and easier to handle solo.

How many fence posts for 100 linear feet?

Posts go at the start, end and between every panel:

• 13 panels = 14 posts (one starter post plus one for every panel)
• Add 1 extra post per gate - gates need posts on both sides for the hinge and the latch

So a 100 ft fence with 8 ft panels and one gate needs 15 posts total. With two gates, 16 posts. With three gates, 17 posts. The fence calculator handles this automatically - run your numbers through the fence calculator to get the exact count.

How many rails do I need?

Pre-built panels come with rails already installed. For a custom-built fence (board on board, horizontal modern, custom picket), rails span between posts:

• 2 rails per section for fences up to 4 ft tall
• 3 rails per section for 5-8 ft tall fences (the middle rail prevents bowing)

Standard rail material is 2x4 pressure-treated lumber set on edge (4 inch dimension vertical) so it resists sagging. Rail length matches your post spacing - typically 8 ft for standard fences.

How many pickets in a picket fence?

Picket count depends on picket width plus the gap between pickets:

• 1x4 pickets (3.5 in actual), 2 in spacing: 5.5 in module → 218 pickets per 100 ft
• 1x4 pickets, 1 in spacing: 4.5 in module → 267 pickets per 100 ft
• 1x6 pickets (5.5 in actual), 2 in spacing: 7.5 in module → 160 pickets per 100 ft
• 1x3 pickets (2.5 in actual), 2 in spacing: 4.5 in module → 267 pickets per 100 ft

The classic American picket fence uses 1x4 pickets with 2 inch spacing - airy enough to see through but solid enough to look like a real fence. Get the full picket and rail breakdown in the wood picket fence calculator.

What size posts should I use?

Post size depends on fence height and wind load:

• 4x4 pressure-treated: standard for 3-6 ft fences in normal wind conditions
• 6x6 pressure-treated: 8 ft fences, high-wind regions and gate posts
• Steel posts (galvanized): longest lasting, used in commercial and security fences

Post length should be the fence height plus 2 feet below grade - so an 8 ft post for a 6 ft fence. In cold climates, dig below the frost line (often 36-48 inches in northern states and Canada) regardless of fence height to prevent frost heave.

How much concrete do I need for fence posts?

For a standard 4x4 post in a 10 inch diameter hole, 30 inches deep, the answer is about 1.5 bags of 60lb concrete per post. For a 100 ft fence with 14 posts, that is 21 bags. For 6x6 posts in 12 inch diameter holes, plan on 3-4 bags per post.

The exact number depends on hole diameter, depth and post size displacement. The post hole concrete calculator handles all of these factors. Use fast-setting concrete (Quikrete Fast-Setting or Sakrete Fast-Setting) for fence posts - it pours in dry, gets watered in and sets in 20-40 minutes, so you can hang the panels the same day.

What about gates?

Every gate adds one post (the extra post on the latch side that does not double as the next panel post). Standard residential gates are 3 ft wide; double gates are 6 ft wide. Plan your gate locations during layout - moving a gate after the posts are set means digging new holes.

Gate posts carry more load than line posts because the gate weight hangs entirely from the hinge post. Use 6x6 posts for any gate over 4 ft wide. Set gate posts at least 36 inches deep regardless of frost line, with extra concrete (3+ bags per gate post).

Fence material quick reference

For a 100 ft, 6 ft tall fence with one gate (2 corners, 1 gate location), broken out by fence type:

• Pre-built panel wood: 12 panels, 15 posts, 22 bags 60lb concrete
• Custom picket (1x4 at 2 in spacing): 218 pickets, 26 rails (2x4x8 ft), 15 posts, 22 bags concrete
• Vinyl panel: 16 panels (6 ft vinyl), 19 posts (broken into end/line/corner/gate types), 38 bags concrete
• Chain link 6 ft: 100 ft fabric, 5 terminal posts, 9 line posts, 10 top rail sections, plus tension bands and ties

Vinyl needs more posts and more concrete than wood because vinyl posts flex and the footing does all the structural work. Chain link uses fewer line posts (10 ft spacing vs 6-8 ft for wood) but adds terminal post hardware that wood does not need.