VPD calculator
VPD = (1 − RH/100) × SVP(Tleaf), SVP = 0.6108 × e17.27T/(T+237.3). Leaf surfaces usually run ~1–2°C cooler than air under LEDs — the offset matters.
VPD: — kPa
Target ranges
See the full VPD / temperature / humidity chart by stage. A journal that logs VPD hourly from a cheap sensor beats any calculator — the number you don't record is the number you can't fix.
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