One input for the fence line — a complete materials list out: posts, rails, pickets and
concrete.
How the fence math works
sections = ceil( length ÷ post spacing )
posts = sections + 1 + gates
rails = sections × rails per section
pickets = length × 12 ÷ (picket width + gap)
concrete = posts × 2 bags (50 lb)
Posts get one extra per gate (each gate hangs on its own post pair, one of which is usually
shared with the fence line). Two 50 lb bags per post suits a 6 ft fence with an 8″ diameter,
30″ deep hole — bump to three bags for 8 ft fences or loose soil.
Lumber shopping guide for a 6 ft privacy fence
| Part | Lumber | Notes |
|---|
| Posts | 4×4 × 9 ft, ground-contact treated | Set 3 ft deep |
| Rails | 2×4 × 8 ft, treated | One per section per row |
| Pickets | 1×6 × 6 ft, cedar or treated | 5½″ actual width |
| Fasteners | 3″ exterior screws (rails), 1⅝–2″ (pickets) | ~6 screws per picket |
Frequently asked questions
How far apart should fence posts be?
8 feet is the standard maximum for wood privacy fences; 6 feet gives a stiffer fence and is required for heavier panels or windy sites. Never exceed 8 feet with dimensional lumber rails.
How many fence posts do I need?
Posts = (fence length ÷ post spacing, rounded up) + 1. A 100 ft run with 8 ft spacing needs 14 posts. Add one extra post for every gate.
How deep should fence posts be set?
Bury one-third of the post height, minimum 24 inches, and below the local frost line. A 6 ft privacy fence uses 9 ft posts set about 3 ft deep, with 2 bags of concrete per post.
How many pickets do I need per foot?
For standard 5.5-inch pickets butted tight, about 2.2 pickets per foot; with a 1-inch gap, about 1.85 per foot. A 100 ft privacy fence needs roughly 220 pickets.
How many rails does a fence need?
Two rails for fences up to 4 ft tall, three rails for 5–6 ft, and four for 8 ft. Rails are usually 2×4s cut to your post spacing.