Fence Calculator
Count the posts, rails, pickets and concrete you need for a wood picket or privacy fence.
How to use this fence calculator
Measure the full run of the fence in feet. For a fence with corners, add up all the sides. Most wood fences have posts every 8 feet, with 2 rails for fences up to 4 feet tall and 3 rails for 6-foot privacy fences. Use a gap of 0 for a solid privacy fence, or around 2–3 inches for a classic picket look. The calculator assumes 4×4 posts, which are 3.5 inches square.
How deep should fence posts go?
A common rule is to bury one third of the post's total length. Make the hole about three times as wide as the post, and go below your area's frost line. For a 6-foot fence, that usually means an 8-foot post set about 2 to 3 feet deep in a 10–12 inch wide hole.
| Fence height | Post length | Hole depth |
|---|---|---|
| 3–4 ft | 6 ft | about 24 in |
| 5 ft | 8 ft | about 30 in |
| 6 ft | 8–9 ft | 30–36 in |
The math behind it
- Posts = (length ÷ spacing, rounded up) + 1. Add one extra post for each gate.
- Rails = number of sections × rails per section.
- Pickets = length in inches ÷ (picket width + gap), rounded up.
- Concrete = the hole's volume minus the post, multiplied by the number of posts. An 80 lb bag makes about 0.6 cubic feet.
Example: 100 feet of 6-foot privacy fence with posts every 8 feet needs 14 posts, 39 rails (13 sections × 3) and 219 pickets at 5.5 inches wide.
Before you build
- Confirm your property line and check HOA or city rules on height and which side faces out.
- Buy about 5% extra pickets for split or warped boards.
- Use ground-contact rated posts, since they sit in damp soil for years.
Often used together
Quick answers
How far apart should fence posts be?
Most wood fences space posts 6 to 8 feet apart, measured center to center. Closer spacing makes a sturdier fence in windy areas.
How many bags of concrete do I need per fence post?
For a typical 4×4 post in a 10-inch-wide, 30-inch-deep hole, about two 80 lb bags. Larger or deeper holes need more.
How many pickets do I need for a 100 ft fence?
With 5.5-inch pickets and no gaps, about 219. Leaving 2-inch gaps drops that to about 160.