Fence Materials Calculator — ft, posts, boards, cost
How to use this calculator
Enter total fence length and height, choose a fence type (privacy, picket, horizontal, or post & rail), then set post spacing, post and rail size, and board dimensions. The take-off drives your lumber order — posts, rails, pickets, and 80-lb concrete bags rounded up per hole so you can read it off at the contractor desk.
Fence types — Privacy uses vertical boards with no gaps, Picket adds a gap between boards, Horizontal runs boards flat between posts, and Post & Rail has no infill boards.
Concrete — auto-calculates bags needed per post hole based on post size and depth.
Hardware — optional nails/screws, post caps, and gate hardware.
Saved Calculations
| Time | Length | Height | Posts | Rails | Boards | Concrete | Total $ |
|---|
How to Calculate Fence Materials
Sections = ceil(fence length ÷ post spacing); posts = sections + 1 (line posts plus one end post). Wood-fence post spacing of 6–8 ft o.c. follows common IRC R301 and AWPA practice for residential fences. Pressure-treated 4×4 (3.5″ actual) suits 4–6 ft heights; 6×6 (5.5″ actual) is used for 8 ft or gate posts. Rails are cut to the post spacing, so rail length feeds the same linear-foot tally as posts and boards. For board-foot pricing of the lumber list, cross-check with the board feet lumber calculator.
Concrete for Post Holes
Each post hole is modelled as a cylinder: hole diameter = post width + 4″ for 4×4 or + 6″ for 6×6, depth as selected (2, 2.5, or 3 ft). Hole volume V = π·(d/2)²·depth is divided by the bag yield: an 80 lb bag of concrete mix yields ≈ 0.6 ft³. Typical result is 2–3 bags per 4×4 post and 3–5 per 6×6. Set posts about ⅓ of their length below grade and below the local frost line.
Board and Picket Count
Privacy: boards = (length × 12) ÷ board width. Picket: pickets = (length × 12) ÷ (picket width + gap). Horizontal: boards per section = (height × 12) ÷ board width, times the number of sections. Post & rail has no infill. A 10–15% waste allowance covers off-cuts and culls — the same convention used in the deck board calculator and stud wall calculator. For matching balustrade or top-rail runs, see the railing calculator.
On install day
Three numbers fence crews get wrong. Frost depth — IRC R403.1.4.1 requires footings below the local frost line; most northern states need 36–48″ deep holes, not the 24–30″ that big-box guides show. Gate posts — upsize the two posts flanking any gate to 6×6 even on a 4×4 run, otherwise sag is guaranteed within a season. Concrete price reality — installed wood fence in 2025 USA runs $25–55/lf for 6 ft privacy and $15–30/lf for picket; material alone (this calc) is typically 35–45% of that. Order one extra bag of mix per 10 posts to cover dropped batches and slightly oversized holes.
FAQ
Working in metres? Use the metric fence calculator for the same logic in m and mm with a currency selector. Do gate openings change the count? Gate posts are included in the post total; gate hardware is added under the Hardware section. Why round bags up per post? Each hole is its own pour — you can't share a half-bag between two posts on opposite ends of the run, so rounding per hole matches how the job actually goes.
