How do I space fence pickets evenly?
Work out how many pickets fit, then share the leftover space equally among all the gaps. Between posts 92.5 in apart, 3.5 in pickets with gaps no bigger than 2.5 in need 15 pickets, and the even gap is 2 1/2 in. Mark the first picket that far from the post and then every 6 in on center.
Worked example: an 8 ft section
- Space between 4×4 posts set 8 ft on center: 96 − 3.5 = 92.5 in.
- Pickets: (92.5 − 2.5) ÷ (3.5 + 2.5) = 15, so 15 pickets fit with gaps of at most 2.5 in.
- Wood used by the pickets: 15 × 3.5 = 52.5 in, which leaves 40 in of open space.
- There is one more gap than pickets: 40 ÷ 16 = 2.5 in per gap.
- On center: 3.5 + 2.5 = 6 in from one picket to the next.
Here the numbers come out even. When they do not, the calculator rounds the picket count up so every gap stays under your limit and shows the exact gap to the nearest 1/16 in.
Pickets per 8 ft section
For 92.5 in between posts, the space left by 4×4 posts set 8 ft on center.
| Picket width | Largest gap | Pickets | Even gap | On center |
|---|---|---|---|---|
| 3.5 in | 1 in | 21 | 7/8 in | 4 3/8 in |
| 3.5 in | 1.5 in | 19 | 1 5/16 in | 4 13/16 in |
| 3.5 in | 2 in | 17 | 1 13/16 in | 5 5/16 in |
| 3.5 in | 2.5 in | 15 | 2 1/2 in | 6 in |
| 3.5 in | 3 in | 14 | 2 7/8 in | 6 3/8 in |
| 5.5 in | 1 in | 15 | 5/8 in | 6 1/8 in |
| 5.5 in | 2 in | 13 | 1 1/2 in | 7 in |
| 5.5 in | 3 in | 11 | 2 11/16 in | 8 3/16 in |
How to lay out the pickets
- Cut a spacer block to the even gap and use it between every picket.
- Or mark the on-center spacing along the top rail with a tape, starting from the first gap.
- Check every few pickets with a level so the boards stay plumb.
- For pool fences, local barrier rules can limit the gap between pickets. Check them before choosing the gap.
How the calculator works
Pickets = (space − largest gap) ÷ (picket width + largest gap), rounded up
Even gap = (space − pickets × picket width) ÷ (pickets + 1)
On center = picket width + even gap
The layout has a gap at each post, so there is always one more gap than pickets. To count posts, rails and pickets for a whole fence, use the fence calculator.
Frequently asked questions
How far apart should fence pickets be?
For a spaced picket fence, gaps of about 1.5 to 3 in are common. Privacy fences butt the boards together or leave about 1/4 in.
How do I calculate the gap between pickets?
Subtract the total width of the pickets from the space between the posts and divide by the number of pickets plus one.
How many pickets are in an 8 ft fence section?
With 92.5 in between posts, 3.5 in pickets and gaps of at most 2.5 in, 15 pickets. With 5.5 in pickets and gaps of at most 2 in, 13.
What is on-center spacing?
The distance from the center of one picket to the center of the next, which equals the picket width plus the gap. It is handy for marking a rail with a tape measure.
Sources
- Decks.com, How Far Apart Should Fence Posts Be?
- Inch Calculator, Fence Calculator