Wood Movement Calculator
Estimate across-grain expansion or shrinkage between two moisture conditions and plan movement allowance.
Set up your calculation
An illustrative example is loaded. Replace its values with your measurements, costs or documented settings.
Calculation
Your result
- Across-grain change (+ expands, − shrinks)
- 0.2943 in
- Metric change
- 7.475 mm
- Estimated final width
- 12.2943 in
- Movement at each edge if center-fixed
- 0.1471 in
- Initial → final moisture
- 6.00 → 12.00 %
- Shrinkage used
- 10.5 %
The quote handoff carries your inputs and assumptions. Only an explicit base cost is suggested as a quote cost; prices, rates and measurements remain planning notes.
How it works
With green-to-dry shrinkage fraction S, initial moisture M1 and fiber saturation F: green width = measured width ÷ [1 − S(F−M1)/F]. Movement = green width × S × (M2−M1)/F. Moisture values above F are capped at F. Humidity mode first estimates equilibrium moisture with the Hailwood–Horrobin equation.
- Solid wood across the grain only; engineered panels and lengthwise movement need other data. The species values are approximate averages, not a guarantee for a particular board. Use custom shrinkage for documented material data.
- Humidity estimates assume indoor equilibrium at the same temperature. A moisture meter is more useful for wood that has not acclimated. Half the total movement belongs on each edge only when the panel is fixed at its center.
Reference material
Learn the method in the Academy
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Use this in your project
Continue with the next measurement or cost, then keep the assumptions with your quote.
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