For a straight fence run with posts at the standard 8 feet on center, the count is: divide the fence length by 8, round up, then add 1 for the end post. A 100 ft fence is 13 sections, so 14 posts, and every corner or gate adds one more.
Here are the full material counts by length, and the spacing decisions that change them.
Fence materials by length (6 ft privacy fence)
Counts assume a straight run, posts 8 ft on center, 3 rails per section, and standard 5.5 inch pickets butted tight, with two 60 lb bags of concrete per post:
| Fence length | Posts | Rails | Pickets | Concrete (60 lb) |
|---|---|---|---|---|
| 50 ft | 8 | 21 | 110 | 16 bags |
| 100 ft | 14 | 39 | 219 | 28 bags |
| 150 ft | 20 | 57 | 328 | 40 bags |
| 200 ft | 26 | 75 | 437 | 52 bags |
| 300 ft | 39 | 114 | 655 | 78 bags |
For your exact length, picket size, and gap, the fence calculator computes all four numbers live, and every corner adds one post to whatever it shows.
8 ft or 6 ft post spacing?
8 feet on center is the default because rails come in 8 ft lengths, so nothing gets cut. Drop to 6 ft spacing when:
- the fence is a 6 ft privacy design in a windy area (a solid fence is a sail),
- the ground slopes and sections need to step down,
- you're using lightweight rail stock that would sag over 8 ft.
Six-foot spacing on a 100 ft run means 17 sections and 18 posts, a third more holes to dig, so decide before you order.
How deep do the posts go?
Bury at least one third of the post's above-ground height, minimum 2 feet, and always below your local frost line. A 6 ft privacy fence uses 9 ft posts set about 3 ft deep in a 10 to 12 inch hole. That hole takes roughly two 60 lb bags (or one and a half 80 lb bags) of concrete; gate posts and windy corners justify a wider hole and an extra bag. The concrete footing calculator does the per-hole math for any diameter and depth.
Pickets: the count that surprises people
Standard 5.5 inch pickets butted tight run about 2.2 per linear foot, so a 100 ft privacy fence takes around 219 pickets. Adding a 2 inch gap (spaced picket style) drops it to about 1.6 per foot. Buy a bundle extra either way: some pickets arrive warped or split, and culling them beats hammering them up.
Don't forget
- Call 811 before digging. Free utility marking, and post holes are exactly deep enough to find a gas line.
- Set corner and gate posts first, let them cure, then string a line between them so the run stays straight.
- Gates are their own project: a gate kit, hinges, and a latch per opening, plus beefier posts.
Once the posts are set, the deck stain calculator covers the finishing coat when the fence is ready for it.