Wood Moisture Content Calculator
Calculate the moisture content (MC) of wood using the oven-dry method — the standard technique used in lumber, forestry, and woodworking industries.
grams (or any consistent unit)
grams (or any consistent unit)
Formulas Used
Dry-Basis Moisture Content (standard — ASTM D4442):
MCdry (%) = [(Wwet − Wdry) / Wdry] × 100
Wet-Basis Moisture Content:
MCwet (%) = [(Wwet − Wdry) / Wwet] × 100
Where:
- Wwet = Original (wet/green) weight of the wood sample
- Wdry = Weight after oven-drying to constant mass (typically at 103 ± 2°C)
- Wwet − Wdry = Mass of water evaporated
Conversion between bases:
MCwet = MCdry / (1 + MCdry/100) | MCdry = MCwet / (1 − MCwet/100)
Assumptions & References
- The oven-dry method is the gold standard: samples are dried at 103 ± 2°C until constant mass is achieved (typically 24–48 hours).
- Dry-basis MC is the industry standard in lumber, timber engineering, and wood science (ASTM D4442, ISO 3130).
- Wet-basis MC is used in some agricultural, pulp/paper, and green-wood contexts.
- The fiber saturation point (FSP) is approximately 25–30% MC (dry basis) for most wood species — above this, free water exists in cell cavities.
- Typical equilibrium moisture content (EMC) for interior wood in temperate climates: 6–9% (dry basis).
- Weights must be in the same unit (grams, kg, lbs, oz) — the ratio is dimensionless.
- This calculator assumes no volatile extractives are lost during drying (valid for most structural and furniture woods).
- References: ASTM D4442-20 (Direct Moisture Content Measurement), ISO 3130:1975 (Wood — Determination of moisture content), USDA Forest Products Laboratory Wood Handbook (2021).