Fence Calculator
Enter your fence length, height, and post spacing to find how many posts, sections, and rails you need. Posts are usually spaced 8 feet apart.
How to calculate fence
Divide the fence length by the post spacing (usually 8 ft) and round up to get the number of sections, then add 1 for the final end post. Each section needs a rail roughly every 24 inches of height, 2 rails for a 4 ft fence, 3 rails for a 6 ft fence.
Sections = Length ÷ Spacing (round up) · Posts = Sections + 1
Worked example
A 100 ft wood fence, 6 ft high, with posts every 8 ft.
- Sections = 100 ÷ 8 = 12.5 → 13
- Posts = 13 + 1 = 14
- Rails = 13 sections × 3 = 39
Result: 14 posts, 13 sections, 39 rails
Frequently asked questions
How many fence posts do I need?
Divide the fence length by the post spacing (typically 8 ft), round up for the number of sections, then add 1 for the end post. A 100 ft fence with 8 ft spacing needs 14 posts.
How far apart should fence posts be?
8 feet is the standard spacing for wood, vinyl, and chain-link fences. Closer spacing (6 ft) adds strength in windy areas or for tall privacy fences.
How many rails does a fence need?
Use a rail about every 24 inches of height: 2 rails for fences up to 4 ft, 3 rails for 5–6 ft fences, and 4 rails for 8 ft fences.
How many pickets do I need?
Add the picket width and the gap between pickets, then divide the fence length (in inches) by that total. For 3½-inch pickets with a 2-inch gap, that's one picket every 5½ inches.