Reference chart
Fence Chart & Calculator
Posts, rails, pickets and concrete for a privacy fence at 8-foot spacing with one gate, by fence length, and the same for picket, shadowbox and ranch styles in the calculator. Read the row for your run, then add one post per corner.
Posts, rails, pickets and concrete by fence length
| Length | Sections | Posts | Rails (2×4×8) | Pickets | Concrete bags | Picket style3½″ pickets, 2½″ gap |
|---|---|---|---|---|---|---|
| 20 ft | 3 | 5 | 9 | 46 | 10 | 5 posts · 42 pickets |
| 40 ft | 5 | 7 | 15 | 92 | 14 | 7 posts · 84 pickets |
| 60 ft | 8 | 10 | 24 | 138 | 20 | 10 posts · 126 pickets |
| 80 ft | 10 | 12 | 30 | 184 | 24 | 12 posts · 168 pickets |
| 100 ft | 13 | 15 | 39 | 230 | 30 | 15 posts · 210 pickets |
| 120 ft | 15 | 17 | 45 | 275 | 34 | 17 posts · 252 pickets |
| 150 ft | 19 | 21 | 57 | 344 | 42 | 21 posts · 315 pickets |
| 200 ft | 25 | 27 | 75 | 459 | 54 | 27 posts · 420 pickets |
| 250 ft | 32 | 34 | 96 | 573 | 68 | 34 posts · 525 pickets |
| 300 ft | 38 | 40 | 114 | 688 | 80 | 40 posts · 630 pickets |
| 400 ft | 50 | 52 | 150 | 917 | 104 | 52 posts · 840 pickets |
| 500 ft | 63 | 65 | 189 | 1146 | 130 | 65 posts · 1050 pickets |
Your numbers
8 ft standard; 6 ft in wind or for heavy panels
Posts
21
19 sections + 1 + 1 gate post · 10 ft 4×4s
Rails
57
3 per section, 2×4 × 8 ft
Pickets
344
5.5″ wide, 0″ gap, +5%
Concrete
42 bags
two 50 lb bags per post
sections = ceil(150 ÷ 8) = 19; posts = sections + 1 + gates. Pickets per foot = 12 ÷ (width + gap). Set posts a third of their height in the ground, below frost line.
Questions
How many fence posts do I need?
Length ÷ post spacing, rounded up, plus one, plus one extra post per gate. A 150-foot privacy fence at 8-foot spacing is 19 sections, 20 posts, 21 with a gate. Corners and direction changes each need a post too; add one per corner if the run is not straight.
How far apart should fence posts be?
8 feet for most wood fences, which matches 16-foot rails cut in half and 8-foot pre-built panels; 6 feet for tall privacy fences in windy areas or heavy panels; up to 10 feet for post-and-rail. Vinyl and metal panel systems set their own spacing.
How many pickets for a fence?
12 ÷ (picket width + gap) pickets per foot, times the length, plus 5%. Solid privacy with 5½-inch pickets is 2.18 per foot, 344 for 150 feet with the 5%; a 3½-inch picket fence with 2½-inch gaps is 2 per foot. Shadowbox alternates pickets on both sides and roughly doubles the count.
How deep and how much concrete?
A third of the post's above-ground height below grade, at least 24 inches and below the frost line, in a hole about three times the post width. Two 50-pound bags of fast-setting mix per hole is the usual figure for a 4×4 in a 10-inch hole 30 inches deep; the chart uses that.
What length posts?
Fence height plus depth in the ground, rounded up to stock. The calculator plans 2½ feet in the ground, so a 6-foot fence gets 10-foot 4×4s (8-footers work only with a 2-foot set, the bare minimum) and a 4-foot fence gets 8-footers.
Charts are computed from the formulas and code figures stated on the page (International Residential Code limits where cited). They are planning and take-off numbers, not engineering: species, grade, span tables and local amendments govern anything structural. Confirm with your inspector before you cut.