Wood Moisture Calculator
Wood never stops moving. Enter the current and target moisture of your boards to see the weight change and how much the wood will shrink or swell.
Workshop AI assistant
Describe the piece you want to build and get a complete plan: dimensions, cut list, materials, cost, steps, tools and time.
Workshop assistant
Describe the piece you want to build and get a complete plan: dimensions, cut list, materials, cost, steps, tools and time.
AI-generated results are indicative. Verify dimensions, loads and local codes before building.
How it works
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1
Enter the dimensions of one board and the quantity.
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2
Pick a species — its density and shrinkage coefficients are used.
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3
Set the current and target moisture content (%).
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4
Choose the movement direction: tangential, radial or along the grain.
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5
Calculate to see weight at both levels, water gained or lost, and the size change.
Formula
Weight = volume × density, with density at a given MC = ρ₁₂ × (100 + MC) / 112. Shrinkage = dimension × coefficient × (MC₁ − MC₂). Coefficients: tangential ≈ 0.33–0.66 % per point, radial ≈ 0.23–0.31 % per point, longitudinal ≈ 0.01 % per point, depending on species.
Practical tips
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Target 8–12% MC for indoor furniture, 14–18% for outdoor work.
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Let lumber acclimatize in the room for at least 48 hours before machining.
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The wider the board, the more it shrinks across the width — plan joints accordingly.
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Glue and join wood at the same moisture the piece will live at.
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A moisture meter is the best investment against movement surprises.
Common mistakes
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Buying wet lumber and building the next day.
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Fixing solid wood panels rigidly so they cannot expand.
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Ignoring that wide boards move more than narrow ones.
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Gluing a tabletop while it is still wet, then watching it cup.
Disclaimer
These results are indicative only. Always verify against local building codes, standards and professional advice before building.
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CalculateRelated guides
- How to Calculate Wood Volume The simple formulas to convert board dimensions into cubic meters and board feet.
- Understanding Wood Moisture Moisture content, equilibrium, weight change and shrinkage — the science behind wood that moves.
- Wood Density and Weight Guide A table of common species densities and how to estimate the weight of any board.