How the Shiplap Calculation Works
The key to calculating shiplap is using the **Board Coverage Width**, not the total board width. Shiplap boards are designed to overlap, so a 1x6 board (actual width about 5.5") might only cover **5.25 inches** of wall height per row.
The Steps to Determine Lineal Footage
- **Calculate Total Wall Height in Inches:** For a vertical measurement.
- **Calculate Number of Boards:** Divide the wall height in inches by the board's coverage width in inches. The result is always **rounded UP** to ensure full coverage.
- **Calculate Base Lineal Feet:** Multiply the number of boards by the wall width (in feet).
- **Add Waste:** The base lineal footage is increased by your chosen waste percentage to account for cuts, imperfections, and errors.
Note on Doors and Windows
This calculator provides the total wall area. For projects with doors or windows, you should calculate the lineal footage for the entire wall and subtract the equivalent lineal footage of the cutout area. Alternatively, calculate each separate wall section individually.