Fence Material Estimate: Posts, Rails, and Pickets per Foot

Updated 2026-08-08 · Yardly

A standard 6 ft privacy fence takes about 2 pickets per linear foot, one post every 8 ft plus one, and 3 rails per section — so 100 ft of fence is roughly 14 posts, 39 rails, and 200 pickets before waste. Those three counts come from three separate divisions, and mixing them up is why lumberyard estimates so often come back wrong. Here is each formula, worked on real runs.

The four numbers you are actually buying

A fence quote is four line items, and each one is driven by a different division:

Sections = round up (total length ÷ post spacing)

Posts = sections + 1  •  Rails = sections × rails per section

Pickets = (total length × 12) ÷ (picket width + gap)

Notice that pickets are not derived from the section count. They come from the linear length divided by the picket module. That decoupling is the single most useful thing to understand about fence math: change your post spacing and the picket count does not move at all.

Post concrete is the fifth item and it has its own geometry — the fence post concrete calculator sizes each hole and totals the bags across the run.

Pickets: it is all about the module

The picket module is the width of one board plus the gap beside it. Divide the fence length in inches by that module and you have your count.

Here is the trap: lumber is sold by nominal size but installs at dressed size. A “1×6” picket is 5.5 in wide, not 6 in. Those dressed dimensions are not a manufacturer’s whim — they are fixed by the American Softwood Lumber Standard (Voluntary Product Standard 20), maintained by the American Lumber Standard Committee, which sets the sizes and green/dry relationships that essentially all North American softwood is sold under. Estimate a 100 ft privacy fence at 6 in per board and you order 200 pickets; at the real 5.5 in with no gap you need 219 and you are 19 boards short on install day.

Picket style	Board width	Gap	Module	Pickets per ft	Per 100 ft
Privacy, boards butted	5.5 in (1×6)	0 in	5.5 in	2.18	219
Privacy, expansion gap	5.5 in (1×6)	1/2 in	6.0 in	2.00	200
Semi-privacy	5.5 in (1×6)	1 in	6.5 in	1.85	185
Spaced picket	3.5 in (1×4)	2 in	5.5 in	2.18	219
Ranch / open picket	3.5 in (1×4)	4 in	7.5 in	1.60	160

Two rows in that table land on the same 5.5 in module from completely different designs — a tight privacy fence in 1×6 and an open picket fence in 1×4 both need 219 boards per 100 ft. The style tells you nothing; the module tells you everything.

On the gap question: pressure-treated pickets arrive wet and shrink as they dry, so butting them tight usually produces a fence with 1/4–1/2 in gaps by the second summer anyway. Kiln-dried cedar moves the other way and can swell into a buckle if you leave no room. Either way, a deliberate 1/2 in gap is the forgiving choice, and it is the one the per-foot rule of thumb assumes.

Posts: count sections, then add one

Sections always round up, and posts are always one more than sections — the fence needs a post at both ends of the run.

A 100 ft straight run at 8 ft spacing: 100 ÷ 8 = 12.5 → 13 sections, 14 posts. The last section is a 4 ft remainder, which you either build short or, better, redistribute so all sections land near 7.7 ft and look deliberate.

Corners are the part people double-count. Take an L-shaped yard with a 60 ft run and a 40 ft run:

• 60 ft leg: 8 sections, 9 posts
• 40 ft leg: 5 sections, 6 posts
• Shared corner post counted once: 13 sections, 14 posts

Same totals as the straight 100 ft, because the corner post does double duty. What changes is the kind of post — a corner takes load from two directions and wants a 4×6 or 6×6 with a deeper hole, not another 4×4.

Gates work the opposite way. Each gate adds a heavy post on the latch side beyond the normal line posts, and hanging a 4 ft gate off a standard 4×4 is the most common reason a fence sags within two seasons. Budget one extra 4×6 per gate.

Posts are also the only part of the fence permanently buried in soil, which is why they should be labeled for ground contact rather than above-ground use. The American Wood Protection Association use-category system is what those tags reference — a post rated for above-ground service and set in concrete is a five-year post, not a twenty-year one.

Rails: match the rail length to the spacing

Rails are the easiest count: sections × rails per section.

• 6 ft fence → 3 rails (top, middle, bottom). Long pickets cup without a middle support.
• 4 ft and under → 2 rails is usually fine.
• 100 ft, 13 sections, 3 rails = 39 rails.

The reason 8 ft post spacing dominates residential fencing is that rails ship in 8 ft lengths. Set posts 8 ft on center and each rail spans exactly center to center, butting on the post face with no cutting. Move to 7 ft spacing and every single rail becomes a cut, generating 12.5% waste on the entire rail order plus the labor. If you need tighter spacing for wind, drop to 6 ft so two rails yield from a 12 ft board rather than trimming 8 ft stock.

Worked example: 100 ft with one gate

A 6 ft privacy fence, 8 ft spacing, 1×6 pickets with 1/2 in gaps, three rails, one 4 ft gate:

• Sections: 100 ÷ 8 = 12.5 → 13
• Posts: 14 line/end posts + 1 extra heavy gate post = 15
• Rails: 13 × 3 = 39 (the gate frame is built separately)
• Pickets: 100 × 12 ÷ 6 = 200, and the gate is skinned from that same run of boards, so no separate count is needed → 200, order 220 with waste
• Fasteners: 200 pickets × 3 rails × 2 screws = 1,200. A 5 lb box of #8 × 2 in exterior screws holds roughly 400–450 pieces, so three boxes
• Post concrete: 15 holes at 10 in diameter × 24 in deep ≈ 1.1 cu ft each ≈ 16.5 cu ft ≈ 28 bags of 80 lb mix

That last line is worth a sanity check of its own — 28 bags is well over half a cubic yard, which is the point where hauling starts to matter. How much fence post concrete do I need? walks through the per-hole geometry, and the bag-yield table covers the bags-versus-ready-mix crossover.

Where estimates go wrong

• Measuring the property line instead of the fence line. Fences usually sit inside the line by a few inches and stop at the house, a shed, or an existing neighbor’s fence. Walk it with a wheel, not a plat map.
• Forgetting slope. On a stepped fence, each section drops and the pickets on the low side run longer. Buy the picket length for the tallest step, or you will be splicing.
• Ignoring the last-section remainder. A 4 ft leftover section still needs its full complement of rails, and if you build it as a stub next to 8 ft bays, the fence reads as a mistake from the street.
• Counting gate openings as fence. Subtract gate widths from the run before computing rails, then add the gate frame back as its own small material list.
• Buying posts short. A 6 ft fence with 24 in of burial needs 8 ft posts, and there is no 7 ft length in stock anywhere. Round up to the next standard length and accept the trim.

Keep reading

• Sizing the holes and the mix: the fence post concrete calculator totals concrete across every post in the run.
• Building the whole thing: the fence project estimator rolls posts, rails, pickets, and concrete into one order sheet.
• Per-hole detail and setting technique: how much fence post concrete do I need?

Frequently asked questions