Fence Picket Calculator
Enter your fence length, picket size, and gap to instantly find how many pickets, posts, and rails you need. The calculator also works out concrete for post footings, screw quantities, paintable area, and total material cost. Switch between a traditional single-sided fence and a shadowbox (board-on-board) style, and adjust for a waste factor so you never run short on a lumber run.
How the fence picket calculation works
The fundamental formula is: number of pickets = fence length / (picket width + gap). Because the result is rarely a whole number, the calculator always rounds up so you never run short. The fence length is first converted to inches to match the picket dimensions, then divided by the pitch (width plus gap). A waste factor of 5-15% is added on top to cover off-cuts, twisted boards, and measurement errors. For a shadowbox fence, pickets alternate front and back with a roughly 1-2 inch overlap, which requires about 1.5 times as many pickets as a single-sided fence of the same length.
Posts, rails, and concrete footings
Posts are placed at the ends of each section, so the post count is always one more than the number of sections: (sections + 1). Standard post spacing is 6-8 feet; closer spacing adds strength but uses more posts and concrete. Each section needs 2 or 3 horizontal rails (2x4 lumber) running between the posts. A safe rule of thumb for footing depth is one-third of the total post length buried underground. This calculator estimates footing concrete using an 8-inch diameter cylinder at that depth for each post, and returns the result in cubic yards because that is the unit ready-mix concrete is sold in.
Paint, stain, and finishing coverage
The paintable area shown is the single-side face area of the fence (length x height). If you plan to coat both sides, double this number when buying stain or paint. Typical fence stain covers 150-300 square feet per gallon depending on the wood species and porosity. Pressure-treated lumber should dry for at least 6 months before staining; cedar and redwood can be stained sooner. Add 10-15% for the extra surface area on posts and rail ends.
Material cost estimate
The cost section is optional. Fill in the price per picket, per post, and per linear foot of rail lumber to get a total with tax. Typical 2026 prices at big-box stores run roughly $2-$4 per 6-foot pressure-treated picket, $10-$15 per 8-foot 4x4 post, and $1-$2 per linear foot for 2x4 rail. Cedar costs 20-50% more; redwood can be 2-3 times the price of pressure-treated pine. The estimate covers only the main lumber; add 10-20% for concrete, screws, post caps, gate hardware, and any rentals.
Common fence styles and recommended picket dimensions
| Style | Picket size (nominal) | Actual width | Gap | Notes |
|---|---|---|---|---|
| Privacy (solid) | 1x6 | 5.5 in | 0 in | No visible gap, maximum privacy |
| Shadowbox | 1x6 | 5.5 in | -1 in overlap | Alternating sides, wind-resistant |
| Stockade | 1x3 | 2.5 in | 0 in | Pointed tops, no gap |
| Traditional picket | 1x4 | 3.5 in | 3.5 in | Classic decorative look |
| Spaced privacy | 1x6 | 5.5 in | 0.5 in | Near-full privacy with slight airflow |
| Ranch rail | No pickets | n/a | n/a | Post-and-rail; set picket width to 0 |
Typical lumber sizes and gap settings for the most popular wood fence styles. Actual widths are nominal; actual dimensions are 0.5 in less for width.
Frequently asked questions
How many pickets do I need for 100 feet of fence?
It depends on picket width and gap. With 5.5-inch (1x6) pickets and no gap (privacy fence), you need roughly 218 pickets. With 3.5-inch (1x4) pickets and a 3.5-inch gap (traditional picket style), you need about 171 pickets. Add a 10% waste factor in both cases. Use the calculator above to check any combination of width and gap instantly.
What is the standard gap between fence pickets?
For a privacy fence the gap is 0 inches; for a near-privacy fence 0.5 inch; for a classic decorative picket fence 2-3.5 inches. A gap equal to the picket width (for example, a 3.5-inch gap with 1x4 pickets) creates an evenly spaced look. Check your local zoning or HOA rules, as some limit the maximum gap or require privacy fencing in certain areas.
What is a shadowbox fence?
A shadowbox fence (also called board-on-board) alternates pickets on the front and back of the rails, with each picket overlapping the gap left by the picket on the opposite side. The result is a fence that looks finished from both sides and provides full privacy, while the offset gaps allow more airflow and wind resistance than a solid board fence. It typically requires about 50% more pickets than a single-sided fence of the same length.
How deep should fence posts be set?
A common rule is to bury at least one-third of the post length. For a 6-foot fence using 9-foot posts, that means burying 3 feet. In frost-prone climates, the footing should reach below the frost line (often 36-48 inches) to prevent heaving in winter. This calculator estimates footing concrete at one-third of the total post height (fence height). Check your local building code for the required frost depth in your area.
How much concrete do I need per fence post?
A standard 8-inch diameter footing with a depth of 2 feet (for a 6-foot fence) uses roughly 0.07 cubic feet of concrete per post. For 13 posts that is about 0.9 cubic feet total, or just over one 60-pound bag of dry mix per two posts. This calculator uses the cylinder formula (pi x r^2 x depth) for each post and returns the total in cubic yards, which is the unit used for ready-mix orders.
What waste factor should I use when buying pickets?
Use 5% for a simple straight run with no cuts, 10% for a typical residential job with a few corners or a gate opening, and 15% if the terrain is uneven, the fence has many angles, or you are working with a species that is prone to splits and knots (such as some grades of pressure-treated pine). It is always cheaper to buy an extra bundle on the first trip than to make a second supply run.
How many rails do I need per fence section?
Two rails (one near the top, one near the bottom) are standard for fences up to 6 feet tall. Add a third center rail for fences taller than 6 feet, when using heavy lumber like cedar or redwood, or in high-wind areas. Each 2x4 rail runs the full width of one section (post spacing), so total rail footage equals sections x rails x post spacing.