Shiplap Calculator
Estimate shiplap for your project with our free calculator. Get accurate material quantities, costs, and specifications.
Formula
Boards = ceil(Wall Height / Exposure Width) x ceil(Wall Width / Board Length) x (1 + Waste%)
Calculate the number of horizontal rows by dividing wall height by the board exposure width (board width minus overlap). Determine boards per row by dividing wall width by board length. Multiply rows by boards per row, then add your waste factor for cutting and fitting.
Worked Examples
Example 1: Accent Wall in Living Room
Problem: A 12 ft wide x 8 ft tall accent wall using 5.5-inch shiplap boards in 8-ft lengths with 10% waste.
Solution: Wall area = 12 x 8 = 96 sq ft\nExposure width = (5.5 - 0.25) / 12 = 0.4375 ft\nRows = ceil(8 / 0.4375) = 19 rows\nBoards per row = ceil(12 / 8) = 2\nBoards = 19 x 2 = 38\nWith 10% waste = 42 boards
Result: 42 boards, 336 linear feet
Example 2: Bathroom Half-Wall Wainscoting
Problem: A 10 ft wide x 4 ft tall half-wall using 5.5-inch boards in 8-ft lengths with 15% waste.
Solution: Wall area = 10 x 4 = 40 sq ft\nRows = ceil(4 / 0.4375) = 10 rows\nBoards per row = ceil(10 / 8) = 2\nBoards = 10 x 2 = 20\nWith 15% waste = 23 boards
Result: 23 boards, 184 linear feet
Frequently Asked Questions
How do I calculate how much shiplap I need?
Measure your wall width and height in feet to get the total square footage. Then determine how many rows of shiplap boards are needed by dividing the wall height by the board exposure width (actual board width minus the overlap, typically 0.25 inches). Multiply rows by boards per row, then add 10 to 15 percent for waste from cutting, fitting around outlets, and mistakes.
What is the difference between shiplap board width and exposure width?
Shiplap boards have a rabbeted edge that overlaps with the adjacent board. A nominal 6-inch shiplap board typically has an actual width of 5.5 inches, and the exposed face after overlapping is about 5.25 inches. This overlap is what creates the characteristic shadow line between boards. Always calculate material needs using the exposure width, not the full board width, to avoid underestimating.
Should I install shiplap horizontally or vertically?
Horizontal installation is the most traditional and popular orientation, creating the classic farmhouse look with horizontal shadow lines. Vertical installation can make rooms appear taller and works well as wainscoting or accent walls. Diagonal installation creates a dramatic visual effect but produces the most waste (20 to 25 percent) due to angled cuts. Horizontal installation on studs provides the strongest attachment.
How much waste should I plan for with shiplap?
Plan for 10 percent waste on simple rectangular walls with no obstructions. Increase to 15 percent for walls with windows, doors, outlets, or light switches that require cutting. For diagonal installations or complex wall shapes with multiple angles, budget 20 to 25 percent waste. Keeping waste factor adequate prevents delays from running short mid-project and needing to match material from a different batch.
Is Shiplap Calculator free to use?
Yes, completely free with no sign-up required. All calculators on NovaCalculator are free to use without registration, subscription, or payment.
Can I share or bookmark my calculation?
You can bookmark the calculator page in your browser. Many calculators also display a shareable result summary you can copy. The page URL stays the same so returning to it will bring you back to the same tool.