How to Use the VPD Calculator
Calculate Vapor Pressure Deficit to optimize greenhouse climate control:
Enter Air Temperature
Input ambient grow room air temperature in °F.
Enter Relative Humidity
Input room relative humidity percentage (% RH).
Enter Leaf Offset
Measure leaf surface temp using IR thermometer (typically 2°F below air temp under LED lights).
Match Growth Stage
Adjust humidifiers or HVAC to stay within 0.8 - 1.5 kPa target range.
Key Features & Horticulture Science
Leaf Temperature Compensation
Accounts for transpiration cooling effects under LED or HPS grow lighting.
Growth Stage Target Matrix
Provides clear VPD targets for clones, vegetation, early bloom, and late flower.
100% Private Client Compute
Runs in browser memory with zero tracking or server logs.
Horticulture Guide: Vapor Pressure Deficit (VPD) & Stomatal Transpiration
Vapor Pressure Deficit (VPD) combines temperature and relative humidity into a single metric representing drying power of the air. Managing VPD ensures optimal CO₂ intake and calcium transport while preventing fungal pathogens like powdery mildew or botrytis.
Frequently Asked Questions
?What is the ideal VPD for the flowering stage?
The ideal VPD for the flowering stage is between 1.2 and 1.6 kPa.