How to use the board and batten calculator
- Enter the wall width and height.
- Enter the actual batten width (nominal 1×3 boards are about 2½ in wide; 1×4 boards about 3½ in).
- Enter your target spacing and whether it is measured on center or as the gap between battens.
- Choose whether battens sit at both ends of the wall, the stock length you will buy, and a waste allowance.
- Optionally include 4 × 8 backing panels and prices.
How the calculation works
Rather than leaving an awkward narrow gap at one end, the calculator spreads battens evenly. With end battens, the distance between the first and last batten centers is wall width − batten width. That distance is divided into the smallest number of equal intervals that keeps spacing at or below your target; the number of battens is intervals + 1.
Each batten is as long as the wall is tall. Boards to buy depend on how many battens can be cut from one stock board. Backing panels are wall area ÷ 32 sq ft, rounded up.
Formula
- W, H
- Wall width and height
- b
- Batten width
- s
- Target on-center spacing (gap + batten width if you entered a gap)
Worked example
12 × 8 ft wall, 2½ in battens at 16 in on center
Width = 144 in. Span between end batten centers = 144 − 2.5 = 141.5 in. 141.5 ÷ 16 = 8.84 → 9 intervals, so 10 battens at 141.5 ÷ 9 = 15.72 in on center (13.22 in gaps).
Each batten is 8 ft, so one 8 ft board makes one batten: 10 boards, or 11 with 10% waste. Panels: 96 sq ft ÷ 32 = 3, with waste 4 sheets.
Assumptions and limitations
- Doors, windows and outlets are not subtracted. Count battens interrupted by openings separately if needed.
- Horizontal top and bottom rails, trim and caulk are not included.
- Exterior board and batten must follow manufacturer and code requirements for sheathing, water-resistive barriers and fastening.
Frequently asked questions
What is the most common board and batten spacing?
For interior accent walls, battens are often 12-24 in apart; 16 in is popular. Exterior siding commonly uses battens over the board joints, typically at 8-12 in or matched to the panel width.
Should I measure spacing on center or by the gap?
Either works. Choose the one you are planning with. On-center spacing is easier to mark, while the gap is what you see once installed.
Why is my actual spacing different from what I entered?
The calculator adjusts spacing slightly so every gap is identical and the end gaps are not left narrow. The actual spacing is never larger than your target.