VPD, Leaf VPD and Dew-Point Calculator

Air VPD describes the room. Leaf VPD shows the drying pressure at the leaf surface. Dew point shows how close the measured leaf is to forming condensation.

1. Choose Fahrenheit or Celsius.
2. Enter canopy-level air temperature and humidity.
3. Measure several leaves and enter a representative leaf temperature.

• Do not assume leaves are always 2°F cooler than the room. The difference changes with light, airflow, and plant water status.
• Use stage ranges as a starting point and track how the cultivar actually responds.
• Check again after lights turn off, when leaf temperature and condensation risk can change quickly.

This calculator does not diagnose plant stress or prescribe one correct VPD for every cultivar and stage. Sensor accuracy and placement matter.

Sources

• FAO: Meteorological data, vapor pressure and dew point
• Corredor-Perilla et al. (2025): Relative humidity and flowering cannabis