By Zencalcy Editorial TeamLast reviewed About us
Shiplap coverage is the board's face width minus the overlap of the rabbet, usually about 1/8 inch per board. Rows are horizontal, so the board count comes from the wall height and the total length from the wall width.
Boards and linear feet for a shiplap wall.
Area = L × W Units = ⌈Area × (1 + waste) ÷ coverage⌉ Cost = Units × price
One board covers about 3.7 sq ft per 8 ft board. Units are rounded up because suppliers sell whole boards, and the waste allowance covers cuts, mistakes and future repairs.
| Symbol | Meaning |
|---|---|
| L, W | Room length and width (or wall length and height). |
| A | Area to cover, in square feet. |
| w | Waste allowance as a percentage. |
| N | Number of boards to buy, rounded up. |
96 sq ft ÷ 3.67 sq ft per board = 27 boards, and 10% waste brings it to 29.
Continue with the Paint Calculator, Wallpaper Calculator, Tile Calculator, or the Flooring Calculator — or browse more home & garden projects and all construction calculators.
Divide the wall height by the board's exposed face width. A 96 inch wall with 5⅜ inch exposure needs 18 rows.
Results use standard construction estimating arithmetic: volumes from measured area and depth, unit weights from published material densities, and code-referenced spans or clearances where the page names a code. Quantities are rounded up to whole saleable units and include the stated waste allowance. These tools are planning aids, not structural design, and do not replace a licensed engineer, a local code check, or a contractor's site measurement.
Reference material used to build and check this calculator:
Last reviewed: September 2026. See how we build and check every tool on the about page.
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Content updated: September 2026