The wood shrinkage calculator predicts how much a board will expand or contract as its moisture content changes. Understanding wood movement prevents cracked glue-ups, binding drawers, and warped table tops — the most common causes of furniture failure.
Wood Movement Calculator
How to Use the Wood Shrinkage Calculator
Wood movement is one of the most overlooked aspects of woodworking. This wood shrinkage calculator gives you the actual dimensional change so you can design joints and panels that accommodate movement rather than fight it.
Setting Initial and Final MC
Initial MC is the moisture content when you mill the wood. Final MC is the equilibrium it will reach in its installed environment. Kiln-dried lumber from a lumber yard is typically 6–8% MC. Installed indoors in a climate-controlled space, it will settle at 6–8% MC. In a workshop with seasonal swings, expect 8–14%. For outdoor use, 15–20% depending on climate.
Flat-Sawn vs. Quartersawn
Quartersawn (vertical grain) wood moves about 40–50% less than flat-sawn (plain-sawn) wood. For a 12\" tabletop panel in white oak, flat-sawn might move 0.26\" seasonally; quartersawn only 0.13\". This matters for solid wood doors, tabletops, and any wide glue-up. When in doubt, use quartersawn for critical applications.
Designing for Movement
Never glue a wide solid wood panel to a perpendicular frame — allow 1/8\" to 3/16\" of movement per foot of width. Use elongated screw slots, Z-clips, or wooden buttons to attach table tops. For drawer fronts, leave a 1/16\" gap per foot of width on each side. Build frame-and-panel doors to let the panel float freely in the groove.
FAQ
Is this wood shrinkage calculator free?
Yes, completely free. All calculations run locally in your browser with no signup required.
How much does wood move per percent moisture change?
Movement depends on species and grain orientation. Flat-sawn (tangential) oak moves about 0.00369 inches per inch per percent MC change. Quartersawn (radial) moves about 0.00181 in/in/%. A 6" flat-sawn oak board might move 0.13" going from 8% to 14% MC — enough to bind a drawer.
What moisture content should wood be at for indoor furniture?
Indoor furniture in most US climates should be at 6–8% moisture content (MC). Kitchens and bathrooms with humidity variation may see 8–14% seasonal swings. Acclimate lumber to your shop's ambient conditions (typically 6–10% MC) before milling.
Does quartersawn wood move less than flat-sawn?
Yes. Quartersawn (vertical grain) wood moves roughly half as much across the width compared to flat-sawn (plain-sawn) wood. This makes quartersawn wood ideal for table tops, doors, and any application where movement must be minimized.
What woods have the least movement?
Teak, mahogany, and cedar have among the lowest shrinkage coefficients due to natural oil content or low density. Domestic options with lower movement include basswood and butternut. High-movement species include hard maple, beech, and white oak (tangential).