Fence Calculator
A 100-foot privacy fence with 8-foot post spacing needs 14 posts, 26 rails, and about 357 pickets using standard 3.5-inch boards. Enter your fence length and spacing to get a full materials count for posts, horizontal rails, and vertical pickets. The calculator works for privacy fences (no gap) and spaced picket fences alike.
Quick answer
Posts are set at regular intervals along the fence line, plus one at each end.
What this tells you
- •Posts are set at regular intervals along the fence line, plus one at each end.
- •Each section between posts gets horizontal rails and a row of vertical pickets.
- •Picket count depends on board width and the gap between boards.
How to Use
- 1Enter the total linear footage of your fence.
- 2Set the fence height in feet (6 feet is the most common privacy fence height).
- 3Enter the post spacing in feet (8 feet is standard for most residential fences).
- 4Choose the number of horizontal rails per section (2 for fences under 6 feet, 3 for taller fences).
- 5Set the picket width in inches and the gap between pickets (0 for a solid privacy fence).
How It Works
Formula
Posts = ceil(Fence Length / Post Spacing) + 1
Sections = Posts - 1
Rails = Sections x Rails per Section
Total Pickets = ceil(Sections x (Post Spacing x 12) / (Picket Width + Gap))The calculator divides the fence into equal sections based on post spacing, then figures out how many pickets fill each section based on board width and gap size. The total is rounded up so you buy full boards.
Calculation note: values are processed in the order shown above, using the current input units.
Worked Examples
100-foot privacy fence
50-foot spaced picket fence
Fence Materials by Length (6 ft height, 8 ft spacing, 3.5 in pickets, privacy)
Quick reference for standard privacy fences with 4x4 posts at 8-foot spacing and 1x6 (3.5-inch actual) pickets with no gap.
| Fence Length | Posts | Sections | Rails (2 per) | Pickets |
|---|---|---|---|---|
| 50 ft | 8 | 7 | 14 | 192 |
| 100 ft | 14 | 13 | 26 | 357 |
| 150 ft | 20 | 19 | 38 | 522 |
| 200 ft | 26 | 25 | 50 | 686 |
These counts assume straight runs with no gates or corners. Add one extra post for each gate opening and each corner.
How Far Apart Should Fence Posts Be?
Most residential wood fences use 8-foot post spacing because standard lumber comes in 8-foot lengths. That means each horizontal rail spans one section without cutting. For areas with high wind, 6-foot spacing gives more strength at the cost of extra posts and labor.
Corner posts and gate posts are always set at the exact corner or opening, regardless of the regular spacing pattern. That often creates one shorter section next to the corner or gate.
Posts should be buried at least one-third of their total length. For a 6-foot fence, use an 8-foot post and set it 2 feet deep. In frost-prone areas, dig below the frost line (typically 36 to 48 inches) to keep posts from heaving.
Wind load matters more than most builders expect. A solid privacy fence acts like a sail. If your area gets sustained winds above 30 mph, consider dropping to 6-foot spacing or adding a third rail for extra rigidity.
Common mistakes
- Forgetting to add extra posts for gate openings on each side of the gate
- Not accounting for corner posts that break the regular spacing pattern
- Ignoring ground slope, which increases the actual fence length compared to the horizontal distance
- Using 2 rails on fences taller than 6 feet instead of 3 for proper wind resistance
- Buying exactly the calculated number of pickets without adding 5-10% for waste and bad boards