Vpd Calculator
Calculate Vapor Pressure Deficit (VPD) from temperature and relative humidity. VPD helps optimize plant growth conditions.
Published by:
isCalculator Editorial Team
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How to use this tool?
How to Use the VPD Calculator
- Enter Temperature – Input the air temperature (e.g., 75). Supports Fahrenheit or Celsius.
- Enter Relative Humidity – Input a value between 0 and 100 (e.g., 60).
- Select Unit – Choose Fahrenheit or Celsius to match your temperature input.
- Click "Calculate VPD" – The result shows Vapor Pressure Deficit in kPa.
- Read the Interpretation – Color-coded feedback tells you if VPD is optimal for growth stages (e.g., vegetative, flowering) or indicates stress risk.
Tip: VPD between 0.4–0.8 kPa is ideal for vegetative growth; 0.8–1.2 kPa for flowering. Values above 1.6 kPa may stress plants.
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Frequently Asked Questions
Vapor Pressure Deficit (VPD) is the difference between the amount of moisture the air can hold when saturated and the amount it actually holds. It affects plant transpiration and growth.
VPD is calculated using temperature and relative humidity. First, compute saturation vapor pressure (SVP) using the Magnus formula, then VPD = SVP × (1 - RH/100).
For vegetative growth, optimal VPD is 0.4-0.8 kPa; for flowering, 0.8-1.2 kPa. Low VPD (<0.4) indicates high humidity; high VPD (>1.2) indicates low humidity.