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Counting pickets for a fence
A fence is a long run of identical pickets, and the count seems like it should be simple: divide the fence length by the picket width. But the gap between pickets changes the answer, and forgetting the gap is how people end up short on the last section. A half inch gap on a hundred foot fence adds up to several feet of extra length, which is several extra pickets.
This estimator divides the fence length by the picket width plus the gap, which is the true space each picket occupies. It then adds your waste allowance for damaged boards, miscuts, and the odd picket that splits when nailed. It also estimates the posts, assuming one post about every eight feet plus one at the end, so you can order posts and pickets together.
The unit toggles let you work in feet or metres for the fence length and in inches or centimetres for the picket width and gap. Enter the units your supplier uses and the estimator converts everything behind the scenes, so a metric fence and an imperial fence both come out right.
A worked example
Take a fence 100 feet long built with 5.5 inch wide pickets and a half inch gap. Each picket occupies 6 inches, or half a foot, so the fence needs 200 pickets before waste. With a 10 percent waste allowance, buy 220 pickets. The post estimate is 100 divided by 8, rounded up, plus one, which gives 14 posts.
Change the gap to zero for a closed privacy fence and the same fence needs only 219 pickets with waste, because each picket now occupies just its own width. Change the gap to 2 inches for a spaced ranch fence and the count falls to about 160 pickets, because the gaps now make up a large share of the fence length. The gap is a design choice as much as a number: it decides how much you can see through the fence.
Posts, rails, and gates
Pickets are only part of a fence. The posts carry the fence, the rails carry the pickets, and the gates need their own hardware and framing. The post estimate here is a starting point, not a layout: real fences need posts at corners, at gates, and wherever the ground changes direction, even if those spots fall between the regular eight foot spacing. Walk the fence line and mark every post position before ordering.
Rails usually run in two or three horizontal rows between posts, depending on the fence height. A four foot fence often needs two rails, while a six foot fence needs three. Count rails separately by multiplying the number of post bays by the rails per bay, and add a waste allowance for rails too, because rail cuts at corners and gates consume length.
Gates deserve their own plan. A gate needs a wider, deeper post on each side, hinges rated for the gate weight, and a latch that a child cannot easily open if the fence encloses a pool or a yard. Order gate hardware with the fence, not after, because a gate built from leftover pickets rarely hangs straight.
Tips for a fence that lasts
Set posts deep enough for your frost line and your soil. A post set too shallow will heave in winter and lean within a year, and no number of pickets will fix a leaning post. Use concrete or compacted gravel around the post according to local practice, and keep the bottom of the pickets slightly above the ground so they do not sit in water and rot.
Buy pickets from the same batch and check them for warping before you start. A warped picket will not sit flat against the rails, and it will stand out along an otherwise straight fence line.
Safety and building codes
This tool is an educational estimator only, never professional advice. Fence results are estimates, so check your local building codes and consult a licensed builder or carpenter before building. Many areas limit fence height, require permits above a certain height, and set rules for fences near sidewalks, corners, and pools. Check property lines too: a fence built even a foot over the line can become an expensive legal problem.
Frequently asked questions
Should the gap be zero for a privacy fence? Usually yes for full privacy, but a tiny gap of an eighth of an inch lets the pickets expand in wet weather without pushing each other out of line. Fully tight pickets can buckle in the first rainy season, so a hairline gap is often wiser than zero.
What if my fence line is not straight? Split it into straight runs, calculate each run separately, and add the results. Each change of direction needs a post, so count those posts in addition to the regular spacing estimate.
How much waste should I add? Ten percent suits a straight run on flat ground. Raise it to fifteen percent for a fence with many corners, gates, or slopes, because every change of direction creates short offcuts that cannot be reused as full pickets.
Enter your fence length, picket width, and gap, choose your units, and take the count to the lumber yard. Walk the line, mark the posts, and check the local rules before you dig the first hole.