Wood movement calculator

Wood swells and shrinks across the grain as the air gets damper or drier. Choose the species and the width of the board, and the humidity at the start and end (for example a heated room in winter at 30 percent and a damp summer at 65 percent).

How it is worked out

Change in width = width × movement coefficient × change in wood moisture content. The coefficient is the share of the width that changes for each 1 percent of moisture; flat-sawn boards move roughly twice as much as quarter-sawn ones. Wood moisture follows the humidity of the air (about 6 percent at 30 percent humidity and 12 to 13 percent at 65 to 70 percent).

An estimate from typical values: real boards differ. Leave room for movement in panels, tabletops and doors, and let wood settle in the room before you build.

Coming soon to the App Store