Picket Spacing Calculator
Enter a run width, your picket width and the gap you want — get the exact even gap and picket count so the last board is never a thin sliver.
↺ Loaded your picket size from a previous calculation. Edit any field to change it.
How to space pickets evenly
The trap with picket spacing is starting at one end with a fixed gap and working across. Almost every time, the run does not divide cleanly and the final picket lands as a thin, obvious sliver. The fix is to reverse the order: decide how many pickets fit the run at roughly your preferred gap, lock that count, then share the leftover space equally across every gap. That is exactly what this calculator does — you get one clean gap number to set your spacer to, and both ends finish on a full picket.
Choosing a gap
- Privacy fence: set the gap to 0. Boards butt tight for a solid face. Leave the tiniest hair of a gap in humid climates so swelling wood does not cup.
- Spaced picket: 2 to 3 inches is the classic open, breezy look that still reads as a fence line.
- Shadowbox / board-on-board: space the front pickets about one picket width apart, then a second row on the back covers the gaps — privacy from straight on, airflow at an angle.
Do it per section, not per fence
Posts are almost never set at identical spacing, so a fence that looks like uniform 8-foot bays might actually run 94 inches in one section and 96 in the next. If you space the whole fence as one number, those small differences pile up and the pattern drifts. Measure each bay between posts and run the calculator for that width — a couple of minutes that makes the finished fence look professionally set.
Account for wood movement
Pressure-treated pickets are often wet when you buy them and will shrink as they dry, widening your gaps by an eighth of an inch or more. Kiln-dried boards do the opposite in wet weather — they swell. If you install soaking-wet lumber, a snug gap will open up nicely; if you install bone-dry boards for a tight privacy look, leave a sliver so they do not buckle against each other later.
How the math works
The run is measured in inches, then divided by one picket plus one gap to estimate how many pickets fit. That count is rounded to a whole number and capped so the pickets can never overlap, giving n pickets and n − 1 gaps. The leftover space — the run minus all the picket faces — is split equally across those gaps to produce the even gap you set your spacer to. The on-center figure (picket width plus gap) is handy if you would rather mark layout lines than use a spacer block.
Estimates only — always dry-fit a few pickets before fastening the whole run.
Frequently asked questions
How do I space fence pickets evenly?
Pick a target gap, then let the math adjust it slightly so a whole number of pickets fits the run. This calculator counts the pickets that fit your run at roughly your target gap, then spreads the leftover space equally across every gap — so you never end up trimming a thin sliver picket at the end.
What is a normal gap between fence pickets?
For a spaced-picket or "good neighbor" look, 2 to 3 inches is common. A shadowbox fence uses about the picket width. A privacy fence uses a 0-inch gap (butted tight) — set the gap to 0 and the calculator treats it as solid. Wood also expands when wet, so if you install dry lumber, a slightly larger gap keeps boards from buckling later.
How do I avoid a thin picket at the end of the run?
Never start laying pickets tight from one end at a fixed gap — the last board almost always lands as an ugly sliver. Instead, fix the picket count first (this tool does that), then divide the run so every gap is identical. A picket at each end with equal gaps between reads as balanced and intentional.
Should I measure each section or the whole fence?
Measure each section between posts and space that section on its own. Posts are rarely spaced perfectly, so a run that is 92 inches in one bay and 94 in the next needs its own gap in each. Run the calculator per section for the cleanest result.
What picket width should I enter?
Enter the actual face width, not the nominal size. A "1x6" picket is really about 5.5 inches wide; a "1x4" is about 3.5 inches. Dog-ear and flat-top pickets share these face widths. Measure one board if you are unsure — a quarter inch across 20 pickets adds up.