Wood Movement Calculator
Movement Coefficients by Species
Dimensional change coefficient per 1% moisture content change.
| Species | Tangential | Radial | T/R Ratio |
|---|---|---|---|
| Red Oak | 0.00369 | 0.00158 | 2.33 |
| White Oak | 0.00365 | 0.00180 | 2.03 |
| Hard Maple | 0.00353 | 0.00165 | 2.14 |
| Cherry | 0.00274 | 0.00126 | 2.17 |
| Black Walnut | 0.00274 | 0.00190 | 1.44 |
| White Pine | 0.00216 | 0.00071 | 3.04 |
| Douglas Fir | 0.00267 | 0.00168 | 1.59 |
| Mahogany | 0.00170 | 0.00125 | 1.36 |
| Teak | 0.00155 | 0.00105 | 1.48 |
| Western Red Cedar | 0.00166 | 0.00081 | 2.05 |
How We Calculate This
This wood movement calculator uses established formulas and industry-standard data to provide accurate estimates.
- Enter your specific values into the calculator fields above
- Our algorithm applies the relevant formulas using your inputs
- Results are calculated instantly in your browser — nothing is sent to a server
- Review the detailed breakdown to understand how each factor affects your result
These calculations are estimates based on standard formulas. For critical decisions, always consult a qualified professional.
How to Convert Oven Recipes to Air Fryer
Wood expands when it absorbs moisture and contracts when it dries. The amount of movement depends on the species, grain orientation, board width, and the magnitude of moisture content change.
The basic rule:
- Formula: Movement = Width × Coefficient × (MC_end − MC_start)
- Tangential (flat-sawn) movement is roughly twice that of radial (quarter-sawn)
- Movement only occurs below the fiber saturation point (~28% MC) — above that, wood dimensions are stable
- Most indoor wood stabilizes at 6-10% MC; seasonal swings of 3-5% MC are common
Always account for wood movement in designs over 6 inches wide. Use breadboard ends, elongated screw holes, and floating panels to allow for seasonal expansion and contraction.
When Would You Use This Calculator?
This wood movement calculator is designed for anyone who needs quick, reliable estimates without complex spreadsheets or professional consultations.
- When you need a quick estimate before committing to a purchase or project
- When comparing different options or scenarios side by side
- When planning a budget and need to understand potential costs
- When you want to verify a quote or estimate you've received from a professional
- When teaching or learning about the concepts behind these calculations
Frequently Asked Questions
How is wood movement calculated?
Movement = Board Width × Species Coefficient × Change in Moisture Content. Each species has a unique coefficient for tangential (flat-sawn) and radial (quarter-sawn) movement, expressed as percentage change per 1% MC change.
What is the difference between tangential and radial movement?
Tangential movement occurs across the growth rings (flat-sawn boards) and is typically 1.5-2× greater than radial movement (across the radius, quarter-sawn boards). Quarter-sawn lumber is more dimensionally stable.
What moisture content should I expect indoors?
In heated homes, wood typically stabilizes at 6-8% MC in winter and 8-12% MC in summer, depending on climate and HVAC. Desert climates may see 4-6%, while humid coastal areas may reach 12-14%.
Does wood move along its length?
Longitudinal movement (along the grain) is negligible — about 0.1% over the full MC range. This is why wood movement is only a concern across the width, not the length.
How can I reduce wood movement?
Use quarter-sawn lumber, apply finish to all surfaces (including ends), choose stable species (teak, mahogany, cedar), or use engineered wood (plywood, MDF). Acclimate lumber to your shop's humidity before building.