Water Activity Calculator
Estimate water activity (aw) from moisture and solute content using Raoult's Law approximation.
Inputs
Results
Water activity (aw)
0.99
Equilibrium RH (%)99.48
Moisture content (%)90.91
Moles of water5.55
Effective moles of solute0.03
Microbial risk zone4
How to Use This Calculator
- Enter water mass and solute mass in grams for your food sample.
- Select the solute type (sucrose, NaCl, or glucose) to apply the correct molecular weight and dissociation factor.
- Enter storage or measurement temperature in °C.
- The calculator shows water activity (aw), equilibrium relative humidity, moisture content, moles of water and solute, and microbial risk zone.
- If aw > 0.91, refrigeration or additional preservatives are required to prevent bacterial growth.
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