On a 12 foot wall with 1x3 battens (2½ inches wide) and a target gap of 16 inches, 9 battens give an exact, even gap of 15 3/16 inches, or 17 11/16 inches on center. With a 1x4 top rail on an 8 foot wall, each batten is cut 7 feet 8½ inches, and the wall takes 81.4 linear feet of trim: twelve 8 foot boards and about 73 nails.
How board and batten spacing is calculated
The trick to a wall that looks right is a batten at both ends and identical gaps in between. With n battens there are n − 1 gaps, so the gap is whatever width is left after the battens, shared equally:
Gap = (wall width − battens × batten width) ÷ (battens − 1)
The calculator first finds the number of battens that brings the gap closest to the spacing you want, then solves for the exact gap. On center (the distance from the middle of one batten to the next, which is also the distance from the left edge of one to the left edge of the next) is the gap plus one batten width.
Battens = round((wall width − batten width) ÷ (target gap + batten width)) + 1
Worked example: a 12 × 8 ft wall
| Step | Numbers | Result |
|---|---|---|
| Battens | (144 − 2.5) ÷ (16 + 2.5) = 7.65, rounded to 8, + 1 | 9 battens |
| Exact gap | (144 − 9 × 2.5) ÷ 8 | 15 3/16 in |
| On center | 15 3/16 + 2½ | 17 11/16 in |
| Batten length | 96 in − 3½ in top rail | 7 ft 8½ in |
| Linear length | 9 × 7 ft 8½ in + 12 ft rail | 81.4 ft |
| Boards | 9 battens + 10% = 10 boards, rail 12 ft + 10% = 2 boards | 12 × 8 ft |
Nails are counted one every 16 inches along each piece plus one at the end: 7 per batten and 10 in the top rail, 73 in all. Bob Vila's advice for interior board and batten is "glue first, and finish with nails", so run a bead of construction adhesive on each batten and use the nails to hold it while the glue sets.
Board and batten spacing: gap or on center?
People mean two different things by "16 inch spacing". Pick the one you mean under "Spacing measured as":
- Gap between battens: the clear space you see. 16 inches on the example wall becomes 15 3/16 inches.
- Center to center: 16 inches on center on the same wall gives 10 battens, 13¼ inches apart, 15¾ inches on center.
No building code sets batten spacing on an interior wall; it is a design choice. Wide gaps (20 inches and more) read as modern and calm, tight ones (12 inches or less) as busy and traditional. Tape a few battens on the wall before you buy.
Batten sizes
| Nominal board | Actual width |
|---|---|
| 1x2 | 1½ in |
| 1x3 | 2½ in |
| 1x4 | 3½ in |
| 1x6 | 5½ in |
These are ProWood's nominal-to-actual sizes; every 1-by board is ¾ inch thick. The calculator always uses the actual width, because a "1x3" that is really 2½ inches wide changes the gap by half an inch per batten.
Top rail, bottom rail and grid
A top rail (usually a 1x4 or 1x6 laid flat) finishes the battens at the ceiling or at a chosen height for a half wall. A bottom rail replaces the baseboard. Both run the full width of the wall and shorten the battens. For a grid of boxes, add rows of horizontal battens: two rows on the example wall split the field into three boxes 29 3/16 inches tall and add 16 short pieces, one in each bay.
On exterior siding the battens cover the joints between wide vertical boards, and Bob Vila says they should overlap each board by at least ½ inch on both sides. Indoors the battens go straight onto the drywall.
Measuring and marking
Measure the wall at the height where the battens will sit, corner to corner. For several walls of the same size, set "Walls like this" and every quantity is multiplied. Walls of different widths each get their own exact spacing, so enter them one at a time: the gap on a 10 foot wall will not be the same as on a 12 foot wall. Mark the first batten flush with the corner, then step off the on-center distance with a story stick instead of a tape, so errors do not add up.
Next steps
- Board and batten on the lower wall only? The wainscoting calculator finds the height by the one-third rule.
- Horizontal boards instead: the shiplap calculator counts boards and nails by row.
- Cutting caps and corners: the miter angle calculator gives the saw settings, and the trim calculator totals linear feet.
- Need to find studs for the nails? The stud calculator shows the framing layout.
- Paint it after: the paint calculator covers walls and trim.
More wall coverings are listed in drywall, paint and walls.