Count fence pickets by clear spans and gate openings
A fence quantity estimate depends on where the measured span starts and ends. The fence picket and gate planner works with clear spans and actual picket widths. It can compare equal end gaps with fixed end clearances, then combine installed pickets, spares and purchase packages. It does not design posts, footings or gate hardware.
Measure between the intended boundaries
Write down the clear distance between the faces that bound each picket span. A post-center dimension includes parts of the posts, so it is not interchangeable with the clear opening. Use the actual width of the selected picket, rather than relying on its nominal product name. Record each span separately when posts or gates interrupt the fence.
Choose a maximum gap for the comparison, then verify the final layout against the product, site requirements and any applicable rules. A number entered in the tool is your planning assumption; the tool does not establish a compliant opening size or assess pool barriers, child safety or animal containment.
Why the end-gap choice changes the count
For a 96-inch clear span, 3.5-inch pickets and a 3.5-inch maximum gap, equal-end mode fits 14 pickets. Their combined width is 49 inches, leaving 47 inches shared among 15 gaps: approximately 3.133 inches each. Both ends have the same clearance as the internal gaps.
Set the fixed end clearance to zero instead. The model now needs 15 pickets. Their width is 52.5 inches, leaving 43.5 inches shared among the 14 internal gaps: approximately 3.107 inches each. The span has not changed; changing the treatment at its ends has added one picket. A layout drawing should make this choice visible before material is ordered.
These results are quantity comparisons. Equal end gaps need not be the correct installation detail next to your post or hardware. In fixed-end mode the tool reserves the chosen clearance at each end before distributing the remaining internal gaps. Check the resulting gap and warnings, rather than assuming that a successful calculation validates the chosen construction detail.
Combine pickets before rounding packages
If the supplier sells seven pickets per package and no spares are selected, the 14-picket example needs two packages. The 15-picket version needs three packages and purchases 21 pickets. When several spans share the same product, combine their required pickets and explicit spares before rounding to packages. Rounding each span separately can overstate the order.
Keep different picket widths, finishes or products in separate purchase groups. Spare pickets are additional physical pieces; a spare setting is not a percentage and should not be silently applied twice. Record purchased pieces minus planned installed pieces so the remainder is visible.
Handle a gate as its own item
A factory-gate row counts a gate leaf rather than turning the whole opening into fence pickets. Split the adjoining fence into its measured clear spans and check the gate manufacturer's required opening, hinges, latch and support details separately. This planner does not calculate hinge clearances or construct a custom gate from loose pickets.
Before buying, keep a worksheet with span labels, actual widths, end-gap mode, calculated count, achieved gap, spare pieces and package size. Re-measure any span that was taken from a drawing rather than the installed boundaries. For construction details use the product references linked in the calculator and the requirements applicable to your site.