Fence material calculator

A wooden fence is four separate materials: pickets for the face, posts for the structure, rails to carry the pickets and concrete under the posts. This calculator counts the first three from the run length, the picket width and the post spacing, so you can price the timber before you dig a single hole.

Fence run length (ft)

Post spacing (ft)

Picket width (in)

A nominal 1x6 dog-ear picket is 5.5 in wide.

Gap between pickets (in)

0 for a solid privacy fence; 1/2 in for a spaced picket fence.

Rails per section (count)

Pickets

214pickets

Posts 14 postsRails 26 railsRail material 200 lin ft

Straight runs with pickets on one side. Board-on-board, shadowbox and lattice-top fences need different counts, and gates need their own frame and hardware.

Pickets are counted across the run, not by area: 100 ft of fence with 5.5 inch pickets and a 1/8 inch gap needs 214 pickets, because each picket plus its gap occupies 5.625 inches of 1,200. Whether you leave a gap is a design choice — solid for privacy, spaced for a traditional look — but the arithmetic changes with it, and a half-inch gap on the same run reduces the count to about 197.

Posts and rails follow the post spacing, which should be planned as even bays rather than a nominal 8 ft with a short one at the end. A 100 ft run at 8 ft gives 13 bays and 14 posts, and rails are counted in linear feet: 26 rails for 13 bays with two rails each, which is 200 linear feet of rail material.

How the calculation works

Posts = ceil(run length / post spacing) + 1. Pickets = ceil((run length x 12) / (picket width + gap)). Rails = sections x rails per section, where sections = posts - 1. Rail footage = rails x the even bay spacing.

• A single straight run with pickets on one side only; a shadowbox or board-on-board fence needs up to twice the pickets.
• Pickets are butted to one another plus the gap, with no allowance for waste — add 5% for cuts and dog-eared ends that split.
• Post spacing is the maximum; the actual spacing is reported and is what you should mark out.
• Concrete, gate hardware, post caps, and the gate itself are not included.

Sources: Nominal 1x6 picket = 5.5 in actual width; Standard maximum post spacing 8 ft for wood fences up to 5 ft with two rails

Worked examples

Questions

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

About 214 with 5.5 in pickets and a 1/8 in gap, or about 197 with a 1/2 in gap. Add 5% for cuts.

How many posts for 100 feet?

14 at 8 ft maximum spacing, giving 13 bays at 7.69 ft. At 6 ft spacing it is 18 posts.

How many rails do I need?

Two per bay for a fence up to 5 ft, three for a 6 ft privacy fence in wind, and three or four for anything taller. Rails are counted per bay, then multiplied by the bay length for footage.

How much concrete per post?

About one 50 lb bag per post in a 10 in hole 2 ft deep, or two bags for a 6x6 corner post. Set the post a third of its length in the ground.

Should I use screws or nails?

Screws for rails and pickets where you want the fence to stay tight; galvanised ring-shank nails are faster and traditional. Either way, use coated fasteners that will not rust-stain the wood.

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Written and maintained by Sam Winters. Last updated 2026-11-04. Every figure is computed in your browser; nothing you enter is sent anywhere. Found an error? Tell me — accuracy reports get fixed first.