Equilibrium Moisture Calculator

The Equilibrium Moisture Calculator determines the equilibrium moisture content (EMC) that materials will reach when exposed to specific temperature and humidity conditions. This is essential for predicting material behavior, storage conditions, and processing requirements.

Modify the values and click the calculate button to use
Material Type
Temperature °C
Relative Humidity %
Temperature Unit  

Related Moisture Content Calculator | Wood Moisture Calculator | Relative Humidity Calculator

Understanding Equilibrium Moisture Content

Equilibrium Moisture Content (EMC) is the moisture content at which a material neither gains nor loses moisture when exposed to specific environmental conditions. It represents the balance point between the material's moisture and the surrounding air.

Key Principles

Sorption Isotherms

The relationship between EMC and relative humidity at constant temperature follows sorption isotherms:

Factors Affecting EMC

Calculation Models

Henderson Model

Commonly used for wood and agricultural products:

EMC = [-ln(1-RH) / A]^(1/B)

Where A and B are material-specific constants

GAB Model (Guggenheim-Anderson-de Boer)

More accurate for wider humidity ranges:

EMC = (M₀ × C × K × RH) / [(1-K×RH) × (1-K×RH+C×K×RH)]

Where M₀, C, and K are material constants

Modified Henderson Model

Includes temperature correction:

EMC = [(-ln(1-RH)) / (A × exp(B/T))]^(1/C)

Where T is absolute temperature

Material-Specific EMC Values

Wood Products

RH (%) 20°C 30°C 40°C
30 6.0% 5.5% 5.0%
50 9.0% 8.5% 8.0%
65 12.0% 11.5% 11.0%
80 16.0% 15.5% 15.0%

Applications

Wood Industry

Agriculture and Food

Textiles and Paper

Practical Considerations

Time to Equilibrium

Hysteresis Effects

Environmental Control

HVAC Design

Storage Facilities

Quality Control Applications

Manufacturing

Testing and Validation

Limitations and Considerations

Note: EMC calculations provide estimates based on established models. Actual values may vary due to material variability, measurement conditions, and environmental factors. For critical applications, verify with experimental measurements.