Exact gap versus even spacing
Keep exact gap preserves the reveal you typed. The working shows module width (picket + gap), a net coverage count for each run, and remaining end space after as many full pickets as fit in the bay. That leftover is where crews rip an end board or nudge the layout in the field.
Even spacing in bays starts from your desired gap to choose how many full pickets belong in each bay, then solves for a uniform gap so those pickets fill the bay: adjusted gap = (bay span − n × width) ÷ (n − 1). Example: a 48 ft run with 7 posts (6 bays of 8 ft) and a 0.5 in target yields about 16 pickets per bay and an adjusted gap near 0.533 in when the layout is possible. If a bay is narrower than one picket, the tool warns that a consistent full-picket layout is impossible.
Nominal versus actual picket width
The field starts at 5.5 inches because NIST Voluntary Product Standard PS 20-25 Table 3 lists that as the minimum dressed-dry width for nominal 6-inch softwood. It is a starting point, not a promise that every dog-ear cedar or specialty picket measures 5.5 in. Measure three boards from the stack you will buy. A small face error repeats hundreds of times along a run.
Multiple runs and end bays
Enter how many separate runs you have. Each run is converted from feet to inches, planned with its own posts and bays, then the picket nets are summed. Do not paste total fence length into one run if the fence is broken by gates or corners — that incorrectly treats separate end bays as one continuous module string. Posts per run set bay count (bays = posts − 1); picket count and post count stay separate on the result blade.
For posts, vinyl, chain-link, and concrete bags on the same project, use the Fence Materials Calculator. Layout context lives on the fence hub.
Waste explanation
Purchase count = ceil(net × (100 + waste%) / 100). The 10% default is a labeled trade convention for culls, splits, and end cuts — not a published standard. Lower it for clean stock and careful dry layout; raise it when end bays need many rips or delivery damage is likely. See the picket spacing guide for worked privacy versus spaced examples.
Exclusions
- Rails and framing lumber
- Gates and gate hardware
- Structural post sizing, frost depth, or wind design
- Fasteners, stain, or concrete bags (concrete lives on the general fence tool)
- Vinyl panels and chain-link mesh (different counting units)