Wood Expansion Calculator
Professional wood expansion calculator for furniture making and construction. Calculate wood movement, seasonal expansion, moisture content effects, and design allowances with species-specific coefficients.
⚠️ WOOD MOVEMENT NOTICE
Wood movement is inevitable and must be accommodated in design. Failure to account for expansion and contraction can result in cracking, warping, or joint failure. Always allow for movement in construction details.
Wood Specifications
Wood Species
Specific Species
Wood Dimensions
Environmental Conditions
Movement Analysis
Enter wood specifications and environmental conditions to calculate expansion, contraction, and design allowances for your project.
Moisture Content
Wood expands and contracts as moisture content changes. Each 1% change in MC causes predictable dimensional change.
Grain Direction
Wood moves most across the grain (tangentially), less radially, and virtually none along the grain length.
Species Variation
Different wood species have varying movement coefficients. Hardwoods generally move more than softwoods.
Seasonal Changes
Humidity and temperature variations cause seasonal wood movement. Plan for worst-case scenarios.
Design Allowances
Provide adequate clearances, expansion joints, and flexible fastening to accommodate movement.
Construction Details
Use proper joinery techniques, floating panels, and movement-friendly hardware to prevent problems.
Frequently Asked Questions
Wood movement varies by species and grain orientation. Typically, for each 1% change in moisture content, wood moves 0.1-0.3% tangentially and 0.05-0.15% radially. A 12" wide oak board might move 1/8" to 1/4" seasonally.
Tangential movement occurs across the growth rings (flat-sawn boards) and is typically 1.5-2x greater than radial movement, which occurs along the growth rings (quarter-sawn boards). This is why quarter-sawn lumber is more stable.
Use proper joinery (floating panels, figure-8 fasteners), orient grain consistently, allow for movement in design, use stable species or engineered materials for critical dimensions, and control environment when possible.
Target 6-8% MC for most indoor environments. This matches typical indoor humidity levels. Wood should be acclimated to the final environment before construction to minimize post-construction movement.
Mahogany, teak, and cedar are among the most stable. Quarter-sawn boards of any species are more stable than flat-sawn. Engineered materials like plywood and MDF have minimal movement.
Dry climates (Southwest US) have lower humidity and less seasonal variation. Humid climates (Southeast US) have higher humidity and greater seasonal swings. Coastal areas have moderate but consistent humidity.