The short answer: a 100 ft wood fence needs about 209 pickets if you use 5.5 in (1×6) boards butted nearly tight for privacy. Switch to a spaced picket look and the number drops. Here is why.
The formula
pickets = fenced length in inches ÷ (picket width + gap), rounded up
A 100 ft run is 1,200 inches. With 5.5 in pickets and a quarter-inch gap, each picket-plus-gap is 5.75 in. So 1,200 ÷ 5.75 = 208.7, which rounds up to 209 pickets.
How width and gap change it
The gap is the biggest lever. Open the boards up to a 1.75 in spaced-picket gap and each picket-plus-gap becomes 7.25 in, so 1,200 ÷ 7.25 ≈ 166 pickets. Narrower 3.5 in (1×4) boards need more pickets but each costs less.
| Picket | Gap | Pickets for 100 ft |
|---|---|---|
| 5.5 in (1×6) | 0.25 in (privacy) | 209 |
| 5.5 in (1×6) | 1.75 in (spaced) | 166 |
| 3.5 in (1×4) | 0.25 in (privacy) | 320 |
Don’t forget gates
You do not clad a gate opening, so subtract each gate’s width from the run before counting. A single 4 ft gate drops a privacy fence by roughly eight pickets.
Get your exact number
Enter the length, picket width and gap in the wood fence calculator and it returns the picket count along with posts, rails and concrete. For even spacing with no thin last board, see the picket spacing guide.