How to Use This Calculator

Enter board width, select wood species, and estimate humidity change between seasons in your area (typically 15-30%). Calculator determines expected movement and gap needed.

Why Accurate Wood Movement Matters

Wood expands and contracts across the grain with moisture changes. Different species move at different rates. Failing to account for movement causes cracking, warping, and joint failures in furniture and woodwork.

Common Mistakes to Avoid

Not leaving expansion gaps, using solid wood in high-humidity areas without planning, gluing cross-grain joints, and assuming plywood behaves like solid wood.

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