Quick answer: For one straight run, divide the length by the post spacing, round up, and add one. A 100 ft fence with 8 ft spacing needs 13 sections and 14 posts. Corners shared between runs do not add extra posts, but each gate usually adds one.
Posts carry the whole fence, so getting the count and spacing right matters. Here is the simple method and how to handle corners and gates.
The Basic Formula
Sections = Fence length ÷ Post spacing (round up)
Posts = Sections + 1 (for one straight run)
Common spacings are 6 ft and 8 ft for wood fences. In the UK, panels are usually 6 ft (1.83 m) wide, so posts are about 1.9 m apart once the post itself is included.
Example: Fence Around a Backyard
A yard fenced on three sides: 60 ft + 100 ft + 60 ft, with 8 ft spacing.
- Sections: 60 ÷ 8 = 7.5 → 8; 100 ÷ 8 = 12.5 → 13; 60 ÷ 8 → 8. Total 29 sections
- Posts: 29 + 1 = 30 posts (the two corner posts are shared)
- Rails, with 2 per section: 58
- Pickets, 3.5 in wide with 0.5 in gaps: 220 ft × 12 ÷ 4 = 660
Gates
A gate opening needs a post on each side. If a gate sits inside a run, it usually adds one post compared with a plain fence. Gate posts should be larger (for example 6×6 instead of 4×4) and set deeper, because they carry the swinging load.
Skip the math: enter the fence length, spacing and height to get posts, rails, pickets or panels and concrete bags. Open the free Fence Calculator →
Posts for Common Fence Lengths
| Fence length | 6 ft spacing | 8 ft spacing |
|---|---|---|
| 50 ft | 10 | 8 |
| 100 ft | 18 | 14 |
| 150 ft | 26 | 20 |
| 200 ft | 35 | 26 |
| 300 ft | 51 | 39 |
How Deep Should Fence Posts Be?
A common rule is to bury one third of the post length, and at least 2 ft (60 cm). A 6 ft fence typically uses 8 ft posts set 2 ft deep. In cold climates, set posts below the frost line to stop frost heave. Make the hole about three times the width of the post.
How Much Concrete per Post?
A 10 inch hole 2 ft deep around a 4×4 post takes about 0.9 cubic feet of concrete, which is roughly two and a half 50 lb bags of fast-setting concrete or two 80 lb bags of standard mix. Our concrete bags guide explains the math.
Before You Dig
- Confirm property lines and local or HOA height limits.
- Call your utility locating service before digging; in the US, dial 811.
- Set the corner and end posts first, then run a string line for the line posts.
- Check each post with a level on two sides before the concrete sets.
Frequently Asked Questions
How far apart should fence posts be?
6 to 8 ft for most wood fences. Shorter spacing makes a stronger fence, especially in windy areas or for tall privacy fences.
How many posts do I need for a 6 ft privacy fence?
Use the same formula; privacy fences often use 6 ft spacing for extra strength. A 100 ft privacy fence at 6 ft spacing needs 18 posts.
Do corner posts count twice?
No. A corner post serves both runs, so count it once.
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