Fence Calculator — Posts, Pickets & Concrete Bags
Who this is for: For fence crews and homeowners quoting a wood run — the picket count at your exact gap, the post-and-bag logistics, and the rails before the lumber yard order.
Perimeter in — posts, rail sections, pickets with your gap spacing, and the concrete bags for setting posts out. Wood privacy and picket fences.
Quick answer: Posts = perimeter ÷ spacing + 1; pickets = perimeter × 12 ÷ (width + gap). A 200-foot run at 8-foot spacing is 26 posts, 25 sections, and 185 pickets per 100 ft at a 1-inch gap — plus ~39 concrete bags.
8 ft standard · 6 ft windy
5.5 in dog-ear standard
0 for privacy
| Post spacing | 8 ft OC standard (6 ft windy) |
|---|---|
| Picket rhythm | width + gap (5.5 + 1 = 6.5 in) |
| Rails | 2 per section (4 ft) · 3 (6 ft privacy) |
| Concrete | ≈1.5 bags (50 lb) per post |
How does the fence calculator count materials?
Posts come from the perimeter divided by your spacing (8 feet on center is the structural default for wood; 6 feet for wind-exposed runs), plus one to close the loop. Rails are sections × rails per section — 2 for a 4-foot fence, 3 for 6-foot privacy. Pickets are the perimeter in inches ÷ (picket width + gap): 5.5-inch pickets with a 1-inch gap run a 6.5-inch rhythm, or about 185 pickets per 100 feet; privacy builds with the gap closed run 218 per 100 feet. Concrete bags assume a 4×4 post in a 10-12 inch hole 24-30 inches deep — about a bag and a half per post, which is the line item everyone forgets at the store.
Common uses
- Ordering pickets by the exact gap before a build
- Counting posts, rails, and bags for a full perimeter run
- Comparing 6-foot vs 8-foot post spacing cost
- Quoting privacy vs spaced-picket builds from one perimeter