How Many Fence Boards Do I Need?
· By DIY Calc
Quick answer: Divide your total fence length (in inches) by the board width plus any gap. For a 100-foot privacy fence using 5.5-inch pickets with no gap, you need about 219 pickets, 14 posts, and 28 rails.
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The Formula (Step by Step)
Step 1: Calculate Pickets
Total fence length (inches) ÷ (board width + gap) = number of pickets
Example: 100 ft = 1,200 inches
1,200 ÷ 5.5 = 218.2 → round up to 219 pickets
Step 2: Calculate Posts
Total fence length ÷ post spacing + 1 = number of posts
Standard post spacing is 8 feet.
100 ÷ 8 + 1 = 13.5 → round up to 14 posts
Step 3: Calculate Rails
Number of sections × rails per section = total rails
13 sections × 2 rails = 26 rails (use 3 rails per section for fences 6 ft+ tall → 39 rails)
Step 4: Calculate Post Concrete
Each post needs 1–2 bags of 50 lb concrete mix (for a standard 4×4 post, 24-inch deep hole).
14 posts × 1.5 bags = 21 bags
Common Fence Board Sizes
- Dog-ear pickets (most common): 5.5 inches wide × 6 ft tall
- 1×6 boards: Actual width 5.5 inches
- 1×4 boards: Actual width 3.5 inches (used for picket fences)
- Shadowbox: Same picket count × 2 (boards on both sides, offset)
Full Material List (100 ft Privacy Fence, 6 ft Tall)
- Pickets: 219 dog-ear boards (5.5" × 6')
- Posts: 14 pressure-treated 4×4 × 8' (buried 2 ft)
- Rails: 39 pressure-treated 2×4 × 8' (3 per section)
- Concrete: 21 bags (50 lb)
- Screws/nails: ~10 lbs of 1.5" exterior screws
- Estimated cost: $1,200–$2,000 (materials only)
Common Mistakes to Avoid
Forgetting about the gate
Subtract gate width from your fence run, but add a gate kit to your list. Gates need extra posts (4×4 minimum, 6×6 for wide gates) and heavy-duty hinges.
Using untreated wood for posts
Always use pressure-treated or cedar for ground contact. Regular pine will rot in 2–3 years. Posts should be rated for ground contact (UC4A or higher).
Setting posts too shallow
Bury posts ⅓ of their total length or at least 24 inches deep — whichever is more. In cold climates, go below the frost line.
Not adding 10% for waste
Boards split, knots happen, and cuts create scrap. Buy 10% extra pickets.
Pro Tips
- Check your property line. Survey stakes save lawsuits. Most jurisdictions require fences to be inside your property line.
- Call 811 before digging. Free utility locating service. Hitting a gas line is not a DIY moment.
- String a line. Use mason's line between corner posts to keep everything straight. Your eye isn't as good as you think.
- Boards should face the neighbor. The "good side out" rule is often a local code requirement, not just courtesy.
Frequently Asked Questions
How much does a wood fence cost per foot?
DIY materials run $12–$20 per linear foot for a 6-foot privacy fence. Professional installation doubles or triples that to $25–$50 per foot.
How far apart should fence posts be?
8 feet on center is standard for most wood fences. Some prefer 6 feet for extra strength, especially in windy areas. Never exceed 8 feet — the rails will sag.
Do I need a permit to build a fence?
Usually yes for fences over 4 feet tall. Check with your local building department. HOAs may have additional restrictions on style, height, and materials.
How long does a wood fence last?
Pressure-treated pine: 15–20 years. Cedar: 15–25 years. Proper maintenance (staining every 2–3 years) extends life significantly.
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Related: Concrete Calculator · Deck Railing Calculator