A shiplap calculator estimates how many boards and what linear footage you need to cover a wall or ceiling. Enter your dimensions and board width to get an accurate material count.
Wall / Ceiling Dimensions
Board Specifications
How to Calculate Shiplap
To calculate shiplap, measure the wall area in square feet, then divide by the coverage per board. Adding a 10% waste factor accounts for cuts at ends and corners.
Choosing Board Width
Narrower boards (3.5-inch) create a more traditional or cottage look with more visible lines. Wider boards (5.5 or 7.25-inch) give a more modern farmhouse feel and go up faster. For accent walls, 5.5-inch is the most popular choice.
Estimates are approximate. Verify measurements before purchasing materials.
Frequently Asked Questions
What width are shiplap boards?
Standard shiplap boards have a face width of 3.5 inches (nominal 4-inch), 5.5 inches (nominal 6-inch), or 7.25 inches (nominal 8-inch). After the tongue and groove overlap, the exposed face is typically 3.5 or 5.5 inches.
How many square feet of shiplap per board?
A 12-foot board with 5.5-inch face covers 5.5 square feet. Multiply board face width in feet by board length to get square footage per board.
How much extra should I buy?
Buy 10% extra for standard installations, 15% for diagonal installations, and 20% for herringbone patterns. Always buy a bit extra for future repairs.
Do I need furring strips under shiplap?
If installing over drywall, no furring strips needed. If installing over studs directly, use 1×3 furring strips 16 inches on center to provide a nailing surface. Always check your local building code.
Is this calculator free?
Yes, completely free with no signup required.