Measure clear infill runs
Calculate pickets between posts or fixed boundaries rather than across gate openings and post widths.
Keep each bay visible when appearance requires centered spacing.
Build the picket module
Module width = actual picket face + intended clear gap for a non-overlapping layout.
Use actual dimensions when count depends on fractions of an inch.
Round and rebalance
Choose a whole picket count and recalculate the resulting equal gap across available clear width.
Check that the adjusted gap still satisfies project requirements.
Add rails, posts, and gates
Picket count alone is not a fence takeoff; rails follow bays and posts follow the structural layout.
Gate pickets can be calculated separately from gate-leaf width.
Verify exterior details
Material movement, treatment, fastener compatibility, grade clearance, wind, and local rules can affect the build.
The quantity calculation does not design the fence.