Water Activity from Equilibrium Relative Humidity
Convert equilibrium relative humidity (ERH) to water activity (a_w) with optional temperature correction for hygroscopic systems.
📖 Need the theory? Read the methodology, assumptions, and equations in the full reference guide.
1. Define Input Parameters
2. Engineering Output
Maximum ERH (ERH_max)
- %RH
- %RH
Temperature difference (delta_T)
- °C
- °C
Corrected ERH (ERH_corr)
- %RH
- %RH
Water activity (a_w)
- dimensionless
- dimensionless
Need this calculation offline?
Download Offline Excel CalculationContext & Assumptions
Water activity quantifies free water availability and drives microbial growth and chemical stability. This calculator converts measured ERH to a_w and applies a linear temperature correction when storage conditions differ from the reference temperature.
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