A 150 ft wood privacy fence 6 ft high, with a 4 ft walk gate and a 10 ft drive gate, takes 20 posts, 51 rails and 297 1x6 pickets. Set 2 ft deep in 10 in holes, the posts need 31 bags of 80 lb concrete — two per hole. The calculator above counts posts, rails, fill, fasteners and concrete for wood privacy, spaced pickets, metal panels or chain link, and draws the line in scale.
How the calculator works
Enter the fence length and height and the gates, choose the fence type, then the posts — size, spacing, depth and hole — and the rails. The result counts posts, rails or top rail, pickets, panels or rolls of mesh, nails, screws or ties, and the concrete in bags, and shows one span in detail.
Posts and gates
Gates stand together at the start of the line and share posts: one post per gate plus one. The rest is fill, split into equal spans no longer than the post spacing: 136 ft at 8 ft is 17 spans of exactly 8 ft, so 17 more posts — 20 in all. Gate posts carry more and are often a size heavier: 4x6 or 6x6 instead of 4x4.
Rails and fill
Two rails hold a fence up to about 6 ft; a 6 ft privacy fence gets three. Each wood rail spans one bay. Pickets are the fill length divided by the picket width plus the gap — 1,632 in ÷ 5½ in = 297 for a tight privacy fence — with two nails per picket at every rail. Metal panels cover their width less one rib of lap; chain link comes in 50 ft rolls on a top rail with a tension wire at the bottom.
Concrete
A post hole is usually three times the post width and a third of the post length deep. The concrete fills the hole less the post: a 10 in hole 2 ft deep around a 4x4 takes 0.92 ft³ — two 80 lb bags. Crown the top so water runs away from the post.
| Hole | Depth | Concrete per post | 80 lb bags |
|---|---|---|---|
| 8 in, 4x4 | 2 ft | 0.53 ft³ | 1 |
| 10 in, 4x4 | 2 ft | 0.92 ft³ | 2 |
| 12 in, 6x6 | 3 ft | 1.73 ft³ | 3 |
Common mistakes
- Posts = length ÷ spacing. Add one for the end and one for each gate.
- Shallow posts. Below the frost line they don't heave; above it they lean in two winters.
- Digging before calling 811. Utility lines are marked for free a few days ahead.
For the concrete alone, use the Concrete Calculator; for the lumber order, the Board Foot Calculator.