Wood Shrinkage Calculator
Calculate wood movement and shrinkage due to moisture content changes
About this calculator
The Wood Shrinkage Calculator helps woodworkers, carpenters, and furniture makers predict how much wood will expand or contract when moisture content changes. Wood is a hygroscopic material that moves with humidity fluctuations, and understanding this movement is crucial for preventing warping, cracking, and joint failure in woodworking projects. This calculator uses wood species data and moisture content values to accurately estimate dimensional changes across the grain, enabling better project planning and material selection.
How to use
Enter your wood species or shrinkage coefficient, initial and final moisture content percentages, and the wood dimension you're measuring. The calculator will compute the expected shrinkage or expansion in inches or millimeters. Use these results to plan for wood movement in your joints, panels, and assemblies.
Frequently asked questions
What moisture content should I use for calculations?
Use your workshop's average humidity conditions. Typically 6-8% for heated indoor spaces, 12-15% for unheated areas, and current moisture meter readings for your specific wood.
Does wood shrink lengthwise along the grain?
Longitudinal shrinkage along the grain is minimal (0.1-0.2%) compared to radial and tangential movement across the grain, which can reach 3-12% depending on species.
Which wood species shrink the most?
Hardwoods like hickory, oak, and maple typically shrink more than softwoods. Quartersawn boards shrink less than plainsawn due to different grain orientations.