VPD Calculator
Calculate the Vapor Pressure Deficit (VPD) of plant leaves to target ideal greenhouse transpiration conditions.
Input Parameters
Enter details for calculation.
Vapor Pressure Deficit
Expert Tip
VPD represents the drying power of air. Maintain 0.8 - 1.2 kPa during vegetative growth and 1.2 - 1.6 kPa during flowering to maximize yield and avoid mildew.
Calculation Methodology & Details
Formula
Uses the Tetens equation to estimate saturated vapor pressures. Tleaf is defined as Tair + Leaf Temp Offset. Humidity inside the leaf stomata is assumed at 100% saturation.
Important Disclaimer
The calculations provided are for educational and general planning guidelines only. They do not replace professional agronomic advice or certified agricultural testing.
How to Calculate VPD
Follow these steps to compute greenhouse VPD values:
Measure Air Temp
Measure the ambient air temperature and relative humidity of the room.
Determine Leaf Temp
Use an infrared thermometer to measure leaf surface temperature to find the offset.
Check Saturation
Find the pressure difference to understand the stomatal transpiration drive.