Fence calculator
Posts, pickets, rails and concrete for a privacy fence. Change the spacing and the count follows.
- Pickets
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- Rails
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- Concrete
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- Sections
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How the calculation works
posts = (length ÷ spacing) + 1, rounded up.
pickets = length × 12 ÷ (picket width + gap), rounded up. Every gap is counted, which is why a 5.5 in picket with no gap yields about 26 pickets per 12 ft section.
rails = sections × rails per section
Worked example
100 ft with 8 ft spacing: 100 ÷ 8 = 12.5 → 13, plus one = 14 posts, 13 sections. Pickets at 5.5 in with no gap: 1,200 ÷ 5.5 = 218.2 → 219 pickets. Rails with 2 per section: 26. Concrete at 2 bags per post: 28 bags.
Post spacing by condition
| Spacing | When | Trade-off |
|---|---|---|
| 6 ft | High wind, tall privacy fence, thin posts | More posts, more concrete |
| 8 ft | Standard residential privacy fence | Balanced cost and rigidity |
| 10 ft | Short decorative fence, low wind | Rails sag over time |
Frequently asked
How deep do posts go?
One third of the post length above ground, minimum. An 8 ft post with 6 ft exposed needs 2 ft in the ground; below the frost line where that applies.
Does the calculator count the end posts?
Yes. Posts = sections + 1, so both ends are included.
Should I use concrete or gravel?
Concrete holds the post upright and resists frost heave. Gravel drains better and is easier to replace. In cold climates, concrete below the frost line is the safer choice.