Redwood Fence Calculator
Estimate premium redwood boards, stringers, posts and concrete needed for standard or board-on-board redwood fences.
Fence calculator
Enter your specs. Every result updates live and shows its formula.
Overview
California Redwood is celebrated for its deep red color, tight grain, and natural resistance to decay, termites, and fire. This tool computes accurate lumber requirements for residential redwood perimeter and privacy enclosures.
Selecting the right grade, such as Construction Heart for posts and ground contact versus Construction Common for pickets, balances premium appearance with cost efficiency.
Assumptions
- Structural posts use Construction Heart redwood or ground-contact pressure-treated timber.
- Horizontal backer rails use 2x4 rough or surfaced lumber spaced on 8-foot centers.
- Hole depths meet local building codes (at least one-third total post length in ground).
- Calculations factor a 10 percent contingency buffer for lumber grading variations and cutoffs.
Common mistakes
- Using sapwood grades (such as Merchantable) below grade or in contact with soil where heartwood is required.
- Fastening redwood boards with un-coated steel hardware that causes severe black galvanic staining.
- Forgetting that board-on-board overlaps require roughly 25 to 30 percent more pickets than flat butted styles.
- Skipping end-cut sealant on redwood posts and cut rails before installation.
Fence calculation formulas
The same math the calculator runs, in plain terms. Nothing here is a black box.
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Sections
sections = max(ceil(effective run / post spacing), 1)
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Post count
posts = (sections + 1) along the run, minus named corner and end posts already placed, plus 2 gate posts per gate
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Effective run
effective run = total length - sum of gate widths
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Rail count
total rails = sections x rails per section
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Picket count
pickets = ceil(run in inches / (picket width + gap)); total = ceil(raw x (1 + waste %))
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Board-on-board pitch
pitch = picket width - 1 in overlap
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Panel count
full panels = floor(run / panel width); add 1 cut panel if the remainder is over 0.01 ft; total = ceil(raw x (1 + waste %))
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Concrete volume
per-hole = pi x (diameter / 2)^2 x depth; total = per-hole x posts; bags = ceil(total / bag yield)
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Slope-adjusted run
slope run = effective run / cos(atan(slope % / 100)); shown alongside, counts use the flat run
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Cost
materials = (posts x post price + rails x rail price + infill x unit price + 60 lb bags x bag price) x regional multiplier; labor = effective run x labor per ft x terrain multiplier x regional multiplier; installed total = materials + gate hardware + removal + permit + labor
Every number the calculator shows comes from these formulas applied to your inputs.
Next step
Related calculators
- Cedar Fence Calculator Calculate cedar pickets, 2x4 rails, 4x4 posts and concrete bags for Western Red Cedar privacy fences with live material estimates.
- Wood fence calculator Calculate posts, rails, pickets and concrete for a pressure-treated pine, cedar or redwood fence. Every formula shown, cost optional.
- Board on board fence calculator Calculate pickets for a board-on-board fence, which overlaps boards for full privacy from both sides, with the overlap built into the formula.
- Shadowbox fence calculator Calculate materials for a shadowbox fence, which alternates pickets on both sides of the rails for a semi-private, two-sided look.
Related reading
In-depth guides
Buying guide
California Redwood carries natural resistance to decay, insects and fire along with a distinctive deep red color and tight grain, which is why it sits at the premium end of the wood fencing species this site covers. The post, rail and picket math behind this page is identical to the general wood fence calculator; what changes with redwood is grade selection, since Construction Heart holds up best for posts and any ground contact while Construction Common, with some lighter sapwood streaks, is the more economical choice for above-ground pickets.
Redwood and cedar are the two natural rot-resistant species on this site and get compared constantly: both need stainless or hot-dipped galvanized fasteners to avoid staining, both benefit from a gravel drainage layer under any post set in concrete, and both cost meaningfully more than pressure-treated pine for a similar service life. The deciding factor is usually regional availability and price rather than performance, since the two perform similarly once installed correctly.
Redwood works in any of the styles this site covers, not just a plain butted layout. Board-on-board overlaps boards for full privacy from both sides at the cost of roughly a quarter more lumber than a butted run, while shadowbox alternates boards with a small gap instead, trading some screening for airflow and a lower board count. The board-on-board vs shadowbox vs solid privacy fence comparison applies the same way to redwood as to any other species, since the style decision is independent of what the boards are made from.
Left unfinished, redwood weathers to a silver grey within a year or two as sunlight oxidizes its tannins, so the fence stain calculator is worth running alongside the lumber order if keeping the natural color is the goal. The fence post calculator covers post spacing and count on its own, and how much does a wood fence cost gives a starting budget range before local redwood pricing is entered here directly. The fence materials guide and fence maintenance guide go deeper on species comparison and long-term care.
Ground-contact applications, meaning any redwood post set directly in soil or concrete, call for a higher grade than above-ground pickets, since sapwood lacks the heartwood's natural rot resistance. Using a lower grade below grade than the application calls for is one of the more common and most consequential mistakes on a redwood job, since it undermines the species' main advantage right at the point where moisture exposure is highest.
End grain on any cut redwood post or rail is more vulnerable to moisture intake than the milled faces, so sealing a field cut before installation is a small step that meaningfully extends the life of that piece, particularly on posts cut to length on site. Combined with stainless or hot-dipped galvanized fasteners throughout, these details protect the premium a redwood job costs over pressure-treated pine, rather than leaving that investment exposed at the cut ends.
Redwood is also available in a range of widths beyond the common 1x6 picket, including wider dimension boards sometimes used for a more contemporary horizontal plank look rather than a traditional vertical picket fence. A horizontal layout changes which dimension counts as the run length and which counts as board width in the underlying formula, so it is worth confirming which orientation a given project is using before entering numbers here.
Sourcing is also a bigger factor for redwood than for the other species this site covers, since true old-growth or wide dimensional redwood is less available than it once was and some regions see it priced and stocked very differently than others. Checking with a local supplier on actual available grades and widths before finalizing a design, rather than assuming the grades referenced generally here are stocked everywhere, avoids a design that cannot actually be sourced as specified.
Redwood also responds differently to different finish types than cedar or pine: a penetrating oil finish tends to suit redwood's tight grain better than a film-forming finish like paint or solid-color stain, which can trap moisture against the wood and peel more readily on redwood's dense surface than on a more porous species. That is a maintenance consideration rather than something that changes the lumber order, but it is worth factoring into the finish choice made alongside the material take-off.
Because redwood is harvested from a more limited geographic range than cedar or pine, availability can shift from season to season at a given supplier, and a project planned around a specific grade or width is worth confirming as in-stock before finalizing a design, rather than assuming the same grade will always be available on short notice the way a more widely milled species typically is.
A simple moisture meter reading on a few boards before installation is a low-cost way to confirm a redwood delivery has dried to a reasonable range, rather than relying on appearance alone, which can be misleading on a dense, tight-grained species like redwood.
Frequently asked questions
What is the best redwood grade for fence pickets?
Construction Heart (Con Heart) offers the best decay resistance, while Construction Common (Con Common) contains some pale sapwood streaks and costs less for above-ground pickets.
Should redwood posts be placed in concrete?
Yes, but the hole must feature 4 to 6 inches of crushed rock at the bottom to allow water drainage. Trowel the top concrete crown to shed rainwater away from the wood.
How many pickets are needed for a 100-foot redwood fence?
For a solid butted privacy fence with standard 1x6 pickets (5.5 in wide), you need roughly 218 to 220 pickets for 100 linear feet, plus waste margin.
Does redwood turn grey if left untreated?
Yes. Without a UV-protective exterior oil or stain, sunlight oxidizes redwood tannins, turning the rich natural amber-red into a weathered silver-grey within 1 to 2 years.
What fasteners work best with redwood fencing?
Always use 304 or 316 stainless steel screws or hot-dipped galvanized ring-shank nails. Never use standard zinc or drywall screws in redwood.
Can you build a shadowbox fence with redwood boards?
Yes. Shadowbox redwood fences allow wind to pass through while providing privacy and displaying a finished look on both neighboring sides.
How do redwood prices compare to pressure-treated pine?
Redwood lumber typically costs 2 to 3 times more than pressure-treated southern yellow pine, but offers higher dimensional stability and fewer warping issues.
How deep should redwood fence posts be embedded?
A standard 6-foot fence requires 8-foot posts buried 24 to 30 inches deep, or below local frost penetration in colder mountain regions.