Board and Batten Spacing Calculator

Clear gap is derived from three inputs: wall width, number of battens, and actual batten face width. Two edge treatments produce different results. Battens at both edges places the first batten flush with the left wall corner and the last flush with the right: Gap = (W − N × b) / (N − 1). Equal end spaces leaves an equal open margin on both sides of the batten group — the more common interior choice: Gap = (W − N × b) / (N + 1). For a 144" wall with 9 battens at 3.5" each, equal end spaces gives (144 − 31.5) / 10 = 11.25".

When you enter a target gap, the calculator solves for N using the inverse formula, rounds to the nearest whole number, then recalculates the exact gap for that whole-number count. The result is the gap your wall will actually have — it may differ slightly from your target, which is unavoidable when fitting a whole number of battens into a fixed width. The calculator displays nearby batten counts alongside their exact gaps so you can compare options before committing.

Not every gap size is achievable for every wall. The available options depend entirely on your wall width and batten face width. A 120" wall with 3.5" battens has different available gaps than a 144" wall with the same battens. This is why it's worth looking at two or three nearby batten counts rather than targeting a single gap size — the closest achievable gap may be meaningfully different from what you had in mind, and an adjacent count might produce a gap you find equally appealing while fitting the wall cleanly.

A gap-to-batten-width ratio of 3:1 to 6:1 is a useful design reference. With 3.5" battens, a gap of 10.5" to 21" falls in this range. Below 3:1, battens start to dominate the wall surface; above 6:1, the open spaces begin to overshadow the battens. Both extremes can look intentional in the right context, but the 3:1–6:1 range tends to produce a balanced result that reads as proportional regardless of room style.

Lumber is sold by nominal size but milled to smaller actual dimensions. A 1×4 board is 3.5" wide, not 4". Entering the nominal size in the calculator makes every calculated gap 0.5" too narrow. On a wall with 9 battens, that's 4.5" of accumulated spacing error — the layout will not fit the wall correctly. Always enter the actual face width, or use the preset buttons which fill in the correct actual dimensions automatically.

Clear gap is the visible open space between two adjacent battens — what you'd measure from the right edge of one batten to the left edge of the next. Center-to-center (CTC) is the distance from the middle of one batten to the middle of the next: CTC = clear gap + batten face width. For a 12" gap with 3.5" battens, CTC = 15.5". Use clear gap when describing how the wall should look; use CTC when marking positions or reading specs that use CTC notation.

The Marks tab gives you the left edge, center, and right edge of every batten measured from the left wall edge — not from the previous batten. These are absolute positions. Measuring from the previous mark accumulates rounding error; on a 12-foot wall with 9 battens, step-measuring can push the last batten nearly a quarter inch off its correct position. Always measure each batten independently from the left wall edge.

Battens at both edges places the first and last battens flush with the wall corners, giving the batten group a framed, corner-to-corner appearance. Equal end spaces leaves the same open margin on both sides as between internal battens — a symmetrical, floating effect. Equal end spaces is the standard choice for interior accent walls because the layout doesn't lock into the corners, which makes it easier to handle walls that aren't perfectly plumb or where corner trim changes the effective width.

To transfer marks to the wall: snap a chalk line at a consistent height, then measure from the left wall edge to each batten's left-edge mark position and make a pencil tick. Extend each tick vertically with a 4-foot level. Always start your tape from the left wall edge for each batten — never step-measure from the previous tick. At corners, plan the end spaces on both sides before marking; for outside corners, install the corner return board first and let it define the batten edge. For inside corners, run one wall's batten tight to the corner, then butt the adjacent wall's batten against it.