How it works
The calculator subtracts gates from the fence length, then counts how many picket-plus-gap widths fit along the rest.
Run = Fence length − Gates and gaps
Pickets = ⌈ (Run + Gap) ÷ (Picket width + Gap) ⌉
Pickets with waste = ⌈ Pickets × (1 + Waste ÷ 100) ⌉
Sections = ⌈ Fence length ÷ Post spacing ⌉ · Posts = Sections + 1
The gap is added once to the run because a row of n pickets has only n − 1 gaps between them. ⌈ ⌉ means rounding up to the next whole picket or post.
All lengths are converted to one internal unit, so you can enter the fence in feet and the pickets and gap in inches, or the fence in metres and the pickets in centimetres. Post counts are for a straight line only; corners, ends and gate posts change the count.
Worked example
Inputs
- Fence length
- 100 ft
- Picket width
- 5 1/2 in
- Gap between pickets
- 0 in
- Gates and other gaps
- 0 ft
- Waste allowance
- 0 %
Result
- Length to cover with pickets
- 100 ft
- Pickets
- 219
Common mistakes
- Using the nominal picket width. A board sold as 6 in wide is 5½ in when dressed, and using 6 in undercounts the pickets.
- Forgetting to subtract gates – or subtracting them twice when the gate itself will carry pickets. Subtract only the openings that get no pickets.
- Treating a corner fence as one straight run when counting posts. Every corner and gate usually needs its own post.
- Buying the exact count with no spares. Split, warped or badly knotted pickets are common, so plan for some extra.
Assumptions and limits
- Pickets are installed in one row, side by side, all the same width with the same gap; n pickets leave n − 1 gaps.
- The waste allowance is added to the picket count and the result is rounded up to whole pickets.
- Posts, if a spacing is entered, are counted for a single straight run over the full fence length (sections = ⌈ length ÷ spacing ⌉, posts = sections + 1).
- Rails, post concrete, fasteners and gate hardware are not included. Post size, depth and spacing are structural decisions – follow your local code or a qualified professional.
Frequently asked questions
How many pickets do I need for a 100 ft privacy fence?
With 5½ in pickets and no gap, 100 ft (1,200 in) ÷ 5.5 in = 218.2, so 219 pickets before any waste allowance. Subtract gates first if they don’t get pickets, and add some extra for damaged boards.
Should I use the nominal or actual picket width?
Always the actual width. The American Wood Council lists a nominal 6 in board as 5½ in dressed and a nominal 4 in board as 3½ in. Measure your pickets or check the product page, because some pickets are sold in other sizes.
How far apart should fence posts be?
That depends on the fence design, the rails, the wind exposure and local rules, so this calculator does not suggest a spacing. Use the spacing from your fence maker’s instructions or your plans, and check with your local building department.
Sources
- NDS Supplement (2018), Table 1A – Nominal and Minimum Dressed Sizes of Sawn Lumber — American Wood Council. Dry dressed sizes: nominal 1 in → 3/4 in, 2 in → 1-1/2 in; widths 4 → 3-1/2 in, 6 → 5-1/2 in.
- NIST Handbook 44, Appendix C – General Tables of Units of Measurement — National Institute of Standards and Technology. Exact unit definitions: 1 in = 2.54 cm, 1 yd³ = 27 ft³, 1 US gal = 231 in³, 1 lb = 0.45359237 kg.
Method reviewed November 2, 2026