VPD Chart Generator with Data Logging

VPD Chart Generator & Logger

Calculate VPD, log your readings, track trends. Data saves to your device only.

VPD Calculator

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Current Conditions

Air Temperature 77°F

Relative Humidity 60%

Leaf Temp Offset -3°F Leaf is usually 1-3°F cooler than air due to transpiration.

Growth Stage Seedling / Clone Vegetative Early-Mid Flower Late Flower 6+

Notes (optional)

Current VPD

0.99

Optimal for Veg

Perfect range. Stomata open, transpiration ideal.

Your Logged Data

0Total Readings

0.00Avg VPD

0.00Min VPD

0.00Max VPD

Date/Time	Temp°F	RH%	VPD	Stage	Status	Notes	Action

Optimal VPD by Growth Stage

Seedling / Clone

0.4 - 0.8 kPa

Temp: 70-78°F
RH: 65-75%
Goal: High humidity, build roots.

Vegetative

0.8 - 1.2 kPa

Temp: 75-82°F
RH: 55-65%
Goal: Rapid growth, max CO2 uptake.

Early-Mid Flower

1.0 - 1.5 kPa

Temp: 75-80°F
RH: 45-55%
Goal: Bud set, mold prevention.

Late Flower 6+

1.2 - 1.6 kPa

Temp: 72-78°F
RH: 40-50%
Goal: Prevent bud rot, boost terps.

Full VPD Chart — Air Temp vs RH

Assumes leaf temp is 3°F below air. Green = optimal 0.8-1.2 kPa. Orange outline = your current reading.

Optimal 0.8-1.2

Acceptable 0.4-0.8 or 1.2-1.6

Too High >1.6

Too Low <0.4