The Face of Your Fence
When building a wooden privacy fence, a picket fence, or a farm fence, the vertical boards (the pickets) make up the vast majority of the visual surface area and represent the largest portion of your lumber cost.
Accurately calculating the number of pickets you need prevents two major headaches: buying too few and having to halt construction to visit the lumber yard, or buying too many and struggling to return dozens of heavy, wet treated boards.
Understanding Picket Widths
Before you can calculate how many pickets you need, you must understand the true, physical width of the lumber you are buying.
Most people buy standard "6-inch" dog-ear privacy pickets. However, just like a 2x4 is not actually 2 inches by 4 inches, a 6-inch picket is a "nominal" measurement. The actual, physical width of a standard 6-inch fence picket is almost universally 5.5 inches (5-1/2").
If you use 6 inches in your mathematical calculations, you will end up drastically short on materials, because every picket is physically smaller than you budgeted for.
The Gap Spacing Variable
The second variable in your calculation is the gap between the boards.
- True Privacy Fence: The boards are butted tightly against each other. The gap is 0 inches. (Note: Treated wood shrinks as it dries. Even if installed with a 0-inch gap, a 1/8-inch gap will naturally appear over the first summer).
- Semi-Privacy (Shadowbox): The boards alternate on either side of the rails, overlapping slightly.
- Picket Fence: Classic white picket fences typically have a gap equal to the width of the picket itself (e.g., a 3.5-inch picket with a 3.5-inch gap).
- Standard Gap: Many builders leave a tiny 0.5-inch gap to allow wind to pass through, which prevents the fence from blowing over in a storm.
How to Calculate Picket Quantities
To find the total number of pickets, you must determine the total "Coverage Width" of a single picket-and-gap combination, and then divide the entire fence length by that number.
The Formula
- Convert the total Fence Length from feet to inches (multiply by 12).
- Add the Picket Width (e.g., 5.5 inches) and the Gap Spacing (e.g., 0 inches) together to find the Total Coverage Width per board.
- Divide the Total Fence Length in inches by the Total Coverage Width.
- Round up to the nearest whole number.
- Add a 5% to 10% waste factor to account for warped boards, split ends, and custom cuts at the corners.
Total Pickets = Roundup((Fence Length × 12) ÷ (Picket Width + Gap Spacing)) × 1.10
Example Calculation
You are building a 100-foot long solid privacy fence using standard 5.5-inch wide pickets. You want them butted tight together (0-inch gap).
- Convert length to inches:
100 ft × 12 = 1,200 inches - Total Coverage Width:
5.5 + 0 = 5.5 inches - Divide total length by coverage:
1,200 ÷ 5.5 = 218.18 pickets - Round up: 219 pickets
- Add 10% Waste:
219 × 1.10 = 241 pickets
You will need to order roughly 241 pickets.
Fasteners: Nails vs. Screws
Once you know your picket count, you must calculate your fasteners. Every standard 6-foot tall privacy picket requires at least 6 fasteners (two driven into the top rail, two in the middle rail, and two in the bottom rail).
If you are buying 241 pickets, you will need nearly 1,500 fasteners.
Always use hot-dipped galvanized or polymer-coated fasteners. Standard bright steel nails will rust within weeks, bleeding dark black streaks down the face of your brand-new cedar or pine fence. While ring-shank nails shot from a pneumatic nail gun are incredibly fast, exterior deck screws are universally considered superior because they allow you to easily remove a single damaged board in the future.