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Shiplap Calculator

Our shiplap calculator will help you estimate the number of shiplap boards needed, as well as the total cost of your decorating project.

Leave at zero to use the dimensions above.
Extra to cover offcuts, breakage and mistakes.
Leave at zero to skip the costing.
Clear
Boards needed3026.48 to cover it, plus 10% waste
Linear length360 ft109.728 m of board in total
Each board covers7.25 sq ft7.25 in effective width × 12 ft
Area to cover192 sq ft
Rows of board20across 12 ft
Board feet217.5figured at 1 in nominal thickness

The method

boards = covered width ÷ board coverage, plus waste

Face width, not nominal width

A “6-inch” deck board is 5½ inches across, and if you leave a ¼-inch drainage gap each board accounts for 5¾ inches of deck. Working from the nominal 6 inches would leave you several boards short over a large deck.

For cladding the same logic applies to the exposure: lapped siding covers less than its width because each course overlaps the one below.