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EMC CalculatorEquilibrium Moisture Content Predictor

Calculate the Equilibrium Moisture Content wood will reach at any temperature and relative humidity. Based on the Hailwood-Horrobin equation used by the USDA Forest Products Laboratory worldwide.

Hailwood-Horrobin ModelTemperature + RH InputCelsius and FahrenheitIndoor/Outdoor PresetsPDF Report
EMC

EMC Calculator

Equilibrium Moisture Content Predictor

Environment Conditions
deg C

Ambient air temperature around the wood.

% RH

Relative humidity of surrounding air (1-99%).

Quick Environment Presets
%

For drying direction analysis.

OK
Equilibrium Moisture Content Results
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% EMC
Equilibrium MC
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direction
Drying Direction
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% MC change
Expected Change
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rating
Use Suitability
ConditionTemperatureRHResulting EMC
Hailwood-Horrobin Calculation
About EMC Calculator
Equilibrium Moisture Content (EMC) is the moisture level at which wood neither gains nor loses moisture when exposed to a constant temperature and relative humidity. Every piece of wood constantly moves toward its EMC. Knowing the target EMC for your climate is the single most important factor in preventing warping, cracking and joint failure.
Where Is This Used?
Kiln Drying OperationsFurniture ManufacturingFlooring InstallationMusical InstrumentsWood Workshops IndiaQuality Control Labs
Formulas Used
Hailwood-Horrobin (USDA FPL standard):W = 330 + 0.452xT + 0.00415xT^2 (T in deg F)k = 0.791 + 0.000463xT - 0.000000844xT^2k1 = 6.34 + 0.000775xT - 0.0000935xT^2k2 = 1.09 + 0.0284xT - 0.0000904xT^2EMC = (1800/W) x [kh/(1-kh) + (k1kh + 2k1k2k^2h^2)/(1 + k1kh + k1k2k^2h^2)]where h = RH/100
Frequently Asked Questions
Why is EMC important for woodworking in India?
India has extreme seasonal humidity swings - from 30% RH in summer to 85%+ during monsoon. Wood dried to 12% MC for AC interiors can swell badly during monsoon. The EMC tells you the correct target moisture for each region and season, preventing costly failures.
What EMC should furniture be dried to?
For air-conditioned interiors: 8-10% MC. For non-AC homes in most of India: 10-12% MC. For coastal/monsoon regions: 12-14%. Always match the EMC of the final service environment, not the workshop.
Does EMC depend on wood species?
EMC is primarily a function of temperature and humidity, nearly identical across species. However, the rate at which wood reaches EMC, and how much it moves dimensionally, varies greatly by species - which is why this tool lets you select a reference species.
ResourcesView the formulasWood Species DatabaseFormula Library
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