Wood Fence Calculator — Posts, Boards, Rails & Materials
Enter your fence length, height, post spacing and board dimensions to get a complete material list: posts, boards, rails and concrete bags — with waste and gate openings accounted for.
ft
ft
ft
in
in
Rails per section
%
18 boards per 8-ft section × 12 solid sections + 10 % waste
- 1
Fence sections
⌈100 ÷ 8⌉ = 13 - 2
Solid sections
13 − 1 = 12 - 3
Boards per section
⌈(8 × 12) ÷ (5.5 + 0)⌉ = 18 - 4
Total boards with waste
⌈18 × 12 × (1 + 10%)⌉ = 238Waste factor: 10% extra for cuts and defects
How does this calculator work?
Posts = ceil(length / spacing) + 1; boards per section = ceil(spacing_in / (boardWidth + gap)); total boards = boards_per_section × solid_sections × (1 + waste%). Post length = fence height + max(height/3, 2 ft) burial depth. Allow 2 bags of 50-lb concrete per post.
Formula
How this is calculated
A standard wood fence is built with vertical posts set in concrete, horizontal rails running between posts, and vertical fence boards (pickets or privacy boards) nailed to the rails. The number of posts equals the number of sections (fence length ÷ post spacing, rounded up) plus one for the final end post. Each post must extend into the ground to prevent frost-heave and wind uplift — a common rule of thumb buries at least one-third of the total post length, with a minimum of 2 feet, so a 6-foot fence typically needs 8-foot posts (6 ft above grade + 2 ft below).
Board count per section is found by dividing the section width (in inches) by the board pitch (board width plus any gap). Multiplying by the number of solid sections and adding a waste factor covers angled cuts, defective boards and measurement errors — 10 % is a typical allowance. Gate openings are subtracted from the solid-section count so you do not over-order boards and rails for those spans.
For concrete, a 50-lb bag of premixed dry-set concrete typically fills a hole roughly 6 inches in diameter and 2 feet deep, which is enough for one post — most contractors use 2 bags per post for a sturdier set. Local soil conditions, frost depth, and wind load can all affect the actual amount of concrete needed; consult your local building code for post size and depth requirements.
Frequently asked questions
6 to 8 feet on centre is the most common range for residential wood fences. Shorter spans (6 ft) are stronger and sag less over time, while longer spans (8 ft) use fewer posts and cost less to install. Never exceed 8 feet with standard 4×4 posts and 2× rails — the rails will bow under the board weight.
The general rule is to bury at least one-third of the total post length, with a minimum of 24 inches. In regions with heavy frost, posts should extend at least 6 inches below the frost line to prevent heaving. A 6-foot fence therefore needs posts buried at least 2 feet deep (ideally more in cold climates), requiring 8-foot or 9-foot posts.
Two rails are sufficient for a 6-foot fence in sheltered areas, but three rails are recommended for tall privacy fences, exposed or windy sites, or heavy boards like cedar. The third rail goes at mid-height and prevents the boards from bowing outward over time.
Also known as
TG we-Calculate Editorial Team. (2026). Wood Fence Calculator — Posts, Boards, Rails & Materials [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/wood-fence-calculator
TG we-Calculate Editorial Team. "Wood Fence Calculator — Posts, Boards, Rails & Materials." TG we-Calculate. 2026. https://we-calculate.com/calculator/wood-fence-calculator.
TG we-Calculate Editorial Team, "Wood Fence Calculator — Posts, Boards, Rails & Materials," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/wood-fence-calculator
@misc{wecalculate_wood_fence_calculator, title = {Wood Fence Calculator — Posts, Boards, Rails & Materials}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/wood-fence-calculator}}, year = {2026}, note = {TG we-Calculate} }
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