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FigureWright

Wood Fence Calculator

Count the boards, rails and posts for a wood fence, including board-on-board, shadowbox and horizontal styles.

Your fence

Units

Changing the style loads typical board sizes for it.

Measure along the fence line, including gate openings.

Height above the ground.

Maximum distance between post centers. 6–8 ft is typical.Maximum distance between post centres. 1.8–2.4 m is typical.

Automatic: 2 up to 4 ft (1.25 m), 3 up to 6½ ft (2 m), 4 above.

Boards

A 1×6 board is 5½ in wide; a 1×4 is 3½ in.Measure the face width of the board.

Use 0 for boards butted together.

Extra boards for cuts, splits and defects. 5–15% is common.

Corners, gates & postsOptional. Defaults: a straight run, no gates, 24 in post depth.

Places where the fence changes direction.

Used for post length and lumber totals. Local rules and frost depth may require more.

Results update as you type. Fractions like 5 1/2 work too.

FigureWright:

Your estimate

Imperial unitsMetric units
Boards
241
incl. 10% waste
Rails
43
3 per section, incl. 10% waste
Posts
14
8 ft long
Linear feet of lumber
1,888
boards + rails + posts
7 ft 8¼ in 6 ft
One section, drawn to scale

Fence line

Total fence line
100 ft
Sections
13
Actual post spacingOn center, with posts spread evenly.
7 ft 8¼ in

Boards

Boards before waste
219
Extra for waste
+ 22
Boards to buyEach 6 ft long (the fence height).
241

Rails

Rails per section
3
Rails before waste
39
Rails to buyEach at least 7 ft 8¼ in long.
43

Posts

End posts
2
Line postsPosts along the straight runs.
12
Total posts
14
Post lengthFence height plus depth in the ground.
8 ft

Linear lumber

Boards
1,446 ft
RailsIncludes the 10% waste allowance.
330 ft
Posts
112 ft
Total
1,888 ft
  • Board, rail and post counts are rounded up to whole pieces.
  • Boards run continuously along the fenced length, across the posts.
  • Linear lumber is a length total to help compare quotes. Buy stock lengths that cut efficiently.

A planning estimate, not a contractor quote. Fence rules, permitted heights, post depth and setbacks vary by location. Check with your local building authority before you build.

What this wood fence calculator does

Choose a style and enter the fence length, height and post spacing, and it counts the boards, rails and posts, with a waste allowance. It also totals the linear feet (or metres) of lumber, which is handy for comparing quotes. Changing the style loads typical board sizes, which you can edit.

How each style is counted

Privacy and picket

One layer of boards along the fenced length, with your chosen gap between them:

boards = ⌈ (length + gap) ÷ (board width + gap) ⌉

A row of n boards has only n − 1 gaps, which is why one gap is added to the length.

Board-on-board

A front layer is spaced so a back layer can cover its gaps, overlapping each neighbouring board by the overlap you set. The gap in the front layer is therefore board width − 2 × overlap. The front layer is counted with the formula above; the back layer has one board fewer, because it only fills the gaps between front boards.

Shadowbox

Boards alternate on either side of the rails. Enter the gap between boards on the same side. Each side is counted like a single layer; the second side has one fewer board. If the gap is narrower than a board, the two sides overlap and the fence is private when viewed straight on.

Horizontal

Boards run from post to post, stacked up the fence height. Rows per section are ⌈ (height + gap) ÷ (board width + gap) ⌉, and each row in each section is one board. Horizontal boards fasten to the posts, so no rails are counted. Long spans often get a vertical center support.

Rails, posts and lumber

Rails are counted per section. Posts use the same logic as the fence post calculator. Linear lumber adds up board length (the fence height for vertical boards), rail length along the fence, and post length (height plus depth in the ground).

Worked example

The calculator opens with a 100 ft privacy fence, 6 ft high, posts at most 8 ft apart, 5½ in boards butted together and 10% waste:

  • Sections: 100 ÷ 8 = 12.5 → 13, so 14 posts spaced 7 ft 8¼ in apart.
  • Rails: 3 per section × 13 = 39, plus 10% = 43 rails.
  • Boards: 1,200 in ÷ 5½ in = 218.2 → 219, plus 10% = 241 boards, each 6 ft long.
  • Lumber: 1,446 ft of boards + 330 ft of rails + 112 ft of posts (14 × 8 ft) = 1,888 linear ft.

Switch the same fence to board-on-board with a 1 in overlap and the front layer is 134 boards, the back layer 133, so 267 boards before waste, about 22% more than the privacy version.

Frequently asked questions

How many boards do I need for a board-on-board fence?

Roughly the fence length divided by (board width − overlap). With 5½ in boards overlapping 1 in on each edge, each board adds about 4½ in of coverage, so 100 ft (1,200 in) takes about 267 boards before waste, about 22% more than a single-layer privacy fence.

What is the difference between board-on-board and shadowbox?

Both use two staggered layers of boards. On a board-on-board fence, both layers are fixed to the same side of the rails and overlap, so there is no see-through gap. On a shadowbox fence, the boards alternate on either side of the rails, so the fence looks the same from both sides and lets air through at an angle.

What are actual board sizes?

Lumber is sold by nominal size. A 1×6 is about 5½ in wide and a 1×4 about 3½ in; a 4×4 post is about 3½ in square. Measure a board from your supplier if you can, because widths vary slightly, and it changes the count.

Should wood fence boards have gaps?

Freshly treated boards are often wet and shrink as they dry, so builders usually butt them tight. Kiln-dried boards may need a small gap to allow for swelling. For picket and horizontal styles the gap is a design choice.

How many rails does a wood fence need?

As a rule of thumb, 2 rails up to about 4 ft tall, 3 rails up to about 6½ ft, and 4 above that. Set it yourself if your design or local practice calls for something different.

Related calculators

How these numbers are worked out, and their limits, is explained on the methodology page.