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Fence Calculator
Fence Calculator
How to use it
- Measure the full fence run in feet (add every side of the yard; gates get subtracted later — a 3 ft gate removes about 3 ft of pickets).
- Pick the height: 4, 6 or 8 ft decides how many rails each section needs.
- Choose post spacing — 8 ft is standard for wood; 6 ft is stronger in windy areas and for 8 ft fences.
- Pick the style: privacy (pickets tight) or picket (2 in gaps). The calculator returns posts, rails, pickets, concrete and screws.
How the fence math works
Posts come first because everything hangs off them. Divide the run by your post spacing and round up — that is the number of sections; posts = sections + 1, because every run has a post at both ends. Rails then follow sections: two rails per section for a 4 ft fence, three for 6 ft and 8 ft, each rail cut to the section length.
Pickets are a coverage count. A standard dog-ear picket is 5.5 in wide; privacy fences butt them together (5.5 in per picket), picket fences leave a 2 in gap (7.5 in per picket). Divide the run in inches by the per-picket coverage and round up, then add 5% — pickets warp, split and arrive with damaged ears. Concrete is estimated at 1½ 60 lb bags per post for a standard 24–30 in deep hole in average soil.
Worked example: 100 ft of 6 ft privacy fence
Post spacing 8 ft: sections = 100 ÷ 8 = 12.5 → 13 sections, posts = 13 + 1 = 14 posts. Rails: 3 per section × 13 = 39 rails (8 ft 2×4s). Pickets: 100 ft = 1,200 in ÷ 5.5 in = 218.2 → 219, plus 5% waste = 230 pickets. Concrete: 14 posts × 1.5 = 21 bags (60 lb). Screws: 230 pickets × 3 rails × 2 = 1,380 screws.
What each number means at the yard
| Item | What to know |
|---|---|
| Posts | 4×4 pressure-treated, rated for ground contact. Buy one extra — the end post you cut wrong is a tradition. |
| Rails | 2×4 rails in the section length (8 ft standard). For 6 ft fences the middle rail stops pickets bowing. |
| Pickets | 5.5 in dog-ear pickets in the fence height. Wet pickets shrink — for privacy fences, install tight and expect small gaps as they dry. |
| Concrete (60 lb bags) | 1.5 bags per post is the average-soil estimate; sandy soil and 8 ft fences need 2. Gravel at the hole bottom improves drainage. |
Fence mistakes that cost money
- Counting posts as length ÷ spacing. That is the section count — you always need one more post to close the run.
- Forgetting the gate. A gate opening needs two heavier posts (often 4×6) and hardware, and removes pickets — plan it before ordering.
- 8 ft post spacing on an 8 ft fence. Tall fences are sails; 6 ft spacing and 3 rails keep them standing in storms.
- No waste on pickets. One in twenty arrives split or twisted; the calculator's 5% keeps you off a second trip.
Fence Calculator — common questions
How many fence pickets do I need per foot?
Privacy style: about 2.2 pickets per foot (12 in ÷ 5.5 in). Picket style with 2 in gaps: about 1.6 per foot. For 100 ft of privacy fence, plan on 219 pickets before waste, 230 with it.
How much concrete does a fence post need?
Roughly 1½ 60 lb bags for a standard post hole (10–12 in wide, 24–30 in deep). Deeper or wider holes, and fence corners, take 2 bags.
Should fence posts be 6 or 8 ft apart?
8 ft is the standard for 4–6 ft wood fences on flat ground. Go 6 ft for 8 ft fences, windy sites, sloped ground or if you want the stiffest result.
How many rails does a 6 ft fence need?
Three per section — top, middle and bottom. Two-rail 6 ft fences let pickets warp and bow within a couple of seasons.
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