Fence Board Calculator
This fence board calculator returns the exact number of boards for board-on-board, shadowbox, and horizontal fence layouts. Enter your length, height, and board style below to get a board count for any run.
Advanced: Picket Width & Gap
13 line + 2 gate, 4x4
With 5% waste: 38 rails, 265 pickets/boards.
Hole: 10 in diameter x 2 ft deep, 0.92 cu ft per post.
Total: 30 bags (80 lb) / 45 bags (60 lb) / 45 bags (50 lb) for 15 posts, 13.81 cu ft.
A fence board calculator handles the three vertical-post layouts that don't fit the simple "boards edge to edge" math of a privacy fence: board-on-board, shadowbox, and horizontal. Each style changes how many 1×6 boards a section needs, sometimes by a wide margin, using the same section framework as every wood fence calculator in the material calculators lineup.
Fence Board Calculator Formula
Every layout on this page shares one formula: find the clear space per section, divide by each board's effective width (its actual width plus any gap, or minus any overlap), round up, then multiply by section count and add 5% waste. The three sections below apply that same fence board calculator formula to board-on-board, shadowbox, and horizontal layouts, since each one only changes the effective width and gap.
Board-on-Board Fence Boards
Board-on-board overlaps each 5.5-inch board by 1 inch on the board next to it, so every board effectively covers only 4.5 inches of run while eliminating any gap a viewer could see through. That 4.5-inch effective width, not the board's full 5.5-inch width, is what you divide the clear section span by.
How to calculate: divide the clear span per section (92.5 inches for an 8-ft section with a 4×4 post) by the 4.5-inch effective width, round up, then multiply by section count and add 5% waste. Worked example, 100 feet, 6 ft tall: 92.5 ÷ 4.5 = 20.6, rounded up to 21 boards per section, times 13 sections = 273 boards, or 287 boards with 5% waste.
Board-on-Board Chart by Length
| Length | Sections | Posts | Boards (raw) | Boards (+5% waste) |
|---|---|---|---|---|
| 50 ft | 7 | 8 | 147 | 155 |
| 100 ft | 13 | 14 | 273 | 287 |
| 150 ft | 19 | 20 | 399 | 419 |
| 200 ft | 25 | 26 | 525 | 552 |
| 300 ft | 38 | 39 | 798 | 838 |
Shadowbox Fence Boards
Shadowbox alternates boards front and back of the rails with a 2.5-inch gap on each side, so the fabric on each side is spaced like a picket fence, but the total count doubles the per-side figure. A 92.5-inch section with 5.5-inch boards and a 2.5-inch gap fits 12 boards per side (92.5 ÷ 8 = 11.6, rounded up), so 24 boards per section total — 312 boards raw for a 100-ft, 6-ft fence, or 328 with waste.
Horizontal Fence Boards by Height
A horizontal layout stacks boards up the height of the fence instead of across its width, so board count per section depends on height, not post spacing or run length.
| Fence height | Height in inches | Boards per section (1×6, 0.5-in gap) |
|---|---|---|
| 4 ft | 48 | 8 |
| 6 ft | 72 | 12 |
| 8 ft | 96 | 16 |
A 100-ft horizontal fence at 6 feet tall across 13 sections needs 156 boards raw, or 164 with 5% waste. An 8-ft horizontal fence on the same run needs 208 raw, or 219 with waste — twice the boards of a 4-ft fence on the identical footprint.
Horizontal fences typically need heavier posts than a vertical layout at the same height, since boards run continuously between posts and put more direct bending load on each post than a vertical picket or privacy layout does. Professionals recommend 6×6 posts for any horizontal fence over 6 feet tall, even where a vertical fence of the same height could use 4×4, and closer post spacing of 6 feet rather than the standard 8 feet for boards longer than 8 feet.
Materials List for a Board Fence
- Boards: 1×6 lumber, cut to fence height plus a couple inches of ground clearance.
- Posts: 4×4 for line posts up to 6 feet, 6×6 for gates and fences over 6 feet.
- Rails: 2×4, with an extra rail row sometimes added on board-on-board and shadowbox layouts to support the doubled board weight on taller fences.
- Fasteners: 2 screws or nails per board per rail, doubled on shadowbox since boards attach on both faces.
If a vertical, edge-to-edge look fits your project better than these overlapped layouts, the picket fence calculator and the fence materials compared guide cover the simpler privacy and picket styles side by side.
Switching board width changes every count on this page without changing the underlying formula. A 1×8 board (7.25 inches actual) on a board-on-board layout with the same 1-inch overlap gives a 6.25-inch effective width, dropping the per-section count from 21 to about 15 for the same 92.5-inch clear span. Wider boards mean fewer pieces to fasten and fewer joints overall, at the tradeoff of a heavier individual board that two people may need to hang plumb.
Post Depth and Concrete
Board-on-board and shadowbox fences carry more lumber weight per section than a simple privacy layout, so don't skimp on post depth — bury at least 2 feet regardless of style, sized on the concrete per fence post calculator. Call 811 before digging.
Waste and Ordering
Add 5% to any board count for cutting errors and warped stock — the difference between 273 raw board-on-board boards and 287 ordered in the worked example. Order boards by the linear foot or bundle where your supplier sells that way, since board-on-board and shadowbox orders run high enough to hit bundle break points quickly.
Sort boards for grain and warp before cutting rather than using them in delivery order — reserving the straightest boards for corners and gate-adjacent sections gives the fence a cleaner line where imperfections show most. Keep a handful of extra boards on hand after the build for future repairs, since matching weathered wood color years later is far harder than pulling from stock set aside at install time.
Next Steps
Once your board count is set, the wood fence cost calculator turns that quantity into an installed cost range for materials and labor.