🪵 Wood Movement Calculator
Pick a species, grain orientation, board width, and moisture range to estimate how far the board will shrink or swell across its width — so you can build in room for seasonal movement.
🧮 Dimensional Change
What is a Wood Movement Calculator?
Solid wood never stops moving — it shrinks as it dries and swells as it takes on moisture, chiefly across the grain. This calculator estimates that change from a species-specific coefficient, the board width, the grain orientation, and the swing in moisture content you expect.
Use it to size expansion gaps, float panels, and choose between flatsawn and quartersawn stock. The coefficients are practical estimates drawn from published shrinkage data — real boards vary, so treat the figure as guidance and always leave a seasonal allowance.
❓ Frequently Asked Questions
Why does wood move after I've built something?
Wood is hygroscopic — it takes on and gives off moisture with the surrounding humidity. As its moisture content changes with the seasons, it shrinks and swells, mostly across the width of the board rather than along its length. Accounting for this movement is what keeps panels from cracking and drawers from sticking.
Does flatsawn or quartersawn wood move more?
Flatsawn (plainsawn) boards move noticeably more across their width than quartersawn boards of the same species, because tangential shrinkage is greater than radial shrinkage. Quartersawn stock is prized for tabletops and doors precisely because it stays flatter and moves less.
How much moisture change should I plan for?
It depends on your climate and whether the piece lives in a heated or humid space. Many shops see finished furniture swing several percentage points of moisture content between a dry winter and a humid summer. Estimate your seasonal range, then leave an allowance so the wood can move without splitting or buckling.
How do I let a wide panel move safely?
Use joinery that allows cross-grain movement: float solid-wood panels in frame-and-panel doors, elongate screw holes or use figure-8 fasteners for tabletops, and account for breadboard-end expansion. The calculator's figure tells you roughly how much room to leave.