Wood Fence Calculator
Enter your fence length, height, style and wood type to get a complete materials list: posts, rails, pickets, concrete bags, screws and estimated cost. Switch between imperial and metric units and see the step-by-step math behind every figure.
How to use this calculator
Enter the total length of fence you need, the height, the spacing between posts, and the width of the boards or pickets you plan to use. Choose your fence style (solid privacy, shadowbox, or spaced picket), your preferred wood type, and how many gate openings to leave. The calculator instantly tells you how many posts, rails, and pickets to buy, how many bags of concrete you need to set the posts, and an estimated total material cost. Switch between imperial and metric units with the Units selector at the top. The step-by-step panel beneath the results shows every calculation so you can verify the math before you head to the hardware store.
How many posts, rails, and pickets does a fence need?
The number of sections is the fence length divided by the post spacing, rounded up to a whole number. You need one post per section plus one extra end post, so a 100 ft fence on 8 ft spacing needs 13 sections and 14 posts. Each section gets two horizontal rails for fences up to 6 ft tall, or three rails for taller fences. The picket count depends on board width and gap: a 6-inch-wide board (actual face 5.5 in) on a solid privacy fence fills a section length with no gaps, so an 8-ft section needs about 18 boards. For picket style with matching gaps, the same formula applies but you add the gap width to the board width in the denominator.
How deep to set fence posts
A standard rule is that at least one-third of the total post length should be buried underground, or at least 2 feet in frost-free climates and deeper where the ground freezes. For a 6-ft fence you would order 8-ft posts, setting 2 ft in the ground. For an 8-ft fence, use 10-ft posts with at least 2.5 ft buried. The concrete collar below should extend 6 inches past the frost depth in your region to prevent heaving. Two 60 lb bags of ready-mix concrete per post is the standard quantity for a 12-inch diameter hole, which is the recommended hole width for 4x4 posts.
Pressure-treated pine vs. cedar vs. redwood
Pressure-treated (PT) pine is the most affordable option and is widely available. It is chemically treated to resist rot, insects, and moisture, giving it a service life of 15-25 years in ground contact. The greenish tint fades over time and it can be painted or stained after it dries out (typically 6-12 months). Western red cedar is naturally rot-resistant due to its oils, easier to work with hand tools, and takes stain beautifully. It costs roughly 1.5-2x as much as PT pine but needs no drying time and smells pleasant. Redwood is the premium option: naturally durable, dimensionally stable, and visually striking. It can last 25-30 years with minimal maintenance but costs 2-3x more than PT pine, and availability varies by region.
Common fence styles: picket specs
| Style | Picket / board width | Gap | Typical height | Best use |
|---|---|---|---|---|
| Solid privacy | 5.5 in (1×6) | 0 in | 6-8 ft | Full screening, pool, backyard |
| Shadowbox | 5.5 in (1×6) | 0 in (alternating) | 6 ft | Privacy + airflow, both sides look finished |
| Dog-ear picket | 3.5 in (1×4) | 3.5 in | 4-6 ft | Front yards, decorative boundary |
| Classic picket | 2.5 in | 2.5 in | 3-4 ft | Garden borders, curb appeal |
| Split rail | 4 in round | Open | 3-4 ft | Property boundary, rustic look |
Typical board sizes and gap widths for common residential wood fence styles.
Frequently asked questions
How many pickets do I need for a 100 ft fence?
For a solid privacy fence using standard 1x6 boards (5.5 in actual face width) on 8 ft post spacing, you need about 218 pickets plus 10% waste (240 boards). For a picket-style fence with 3.5 in gaps on 3.5 in pickets, you need roughly half as many. Use this calculator with your exact dimensions to get a precise count.
How many bags of concrete do I need for fence posts?
The standard is 2 bags of 60 lb ready-mix concrete per post for a standard 12-inch diameter hole 2 feet deep. A 100 ft fence on 8 ft spacing has 14 posts, so you would need 28 bags. Longer post spacings or larger post diameters require more concrete per hole.
What is the standard distance between fence posts?
The most common post spacing for wood privacy and picket fences is 8 feet on center. This matches standard lumber lengths (8-foot rails) and distributes the weight evenly. Some contractors use 6-foot spacing for extra rigidity in windy areas or when using heavier boards.
Do I need 2 or 3 rails per fence section?
Fences up to 6 feet tall typically use 2 horizontal rails: one near the top and one near the bottom. For fences taller than 6 feet, a third rail in the middle is standard practice to prevent bowing and provide a nailing surface for the extra picket length.
How much does it cost to build a wood fence?
Material costs for a standard 6-ft privacy fence run from about $8-15 per linear foot for pressure-treated pine to $15-25 per linear foot for cedar or redwood. Labor from a contractor adds another $15-30 per linear foot, bringing installed costs to roughly $25-55 per linear foot depending on wood type, style, and region. This calculator estimates the materials portion only.
What wood is best for a fence?
Pressure-treated pine is the best value for most budgets: it resists rot and insects, is widely stocked, and lasts 15-25 years. Cedar is the preferred upgrade: naturally rot-resistant, lightweight, and takes stain well without the drying wait of PT pine. Redwood is the top-tier choice for appearance and longevity, but it costs more and is harder to source outside the western United States.