If given enough time, the moisture content of wood will come to an equilibrium with the surrounding environment. The temperature and relative humidity of the surrounding air will establish equilibrium moisture content (EMC) conditions, and the moisture content of the wood in that environment will approach the EMC of the air.
This tool will calculate an estimate of the EMC based on one of the following pairs of data:
- Relative humidity and dry-bulb temperature
- Wet-bulb temperature and dry-bulb temperature
- or Dew-point temperature and dry-bulb temperature
Limitations of This Calculator
Generally, there is good agreement between the calculated EMC from the "EMC Calculate" spreadsheet results and the EMC tables published in the USDA Dry Kiln Operator's Manual. Over the range of dry-bulb temperatures 35°F - 180°F and relative humidities ranging from approximately 20% to 80%, the calculated EMC differs from the tabulated EMC by no more than 0.5% EMC, and in the majority of instances differs by no more than 0.2% EMC. The larger errors occur at the higher dry-bulb temperatures (160°F - 180°F). As pointed out in the Dry Kiln Operator's Manual (page 40), the least square regression used to fit the tabulated EMC data and generate the coefficients used by the sorption equation "give estimates close to but not exactly the same as those in the tables."