GrowTools

🌿 VPD Calculator

Air Temp (°C)

Relative Humidity (%)

Leaf-to-Air Offset (°C)

Growth Stage

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kPa · Vapour Pressure Deficit

0.00.40.81.21.6+

Air SVP

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Leaf SVP

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Leaf Temp

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Actual VP

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VPD = Leaf SVP − (RH% × Air SVP / 100). A leaf offset of −2 °C is a common default under HID/LED lighting.

⏱ Time Calculator

Start Time (HH:mm)

End Time (HH:mm)

Duration

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🌙 Overnight span

Hours

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Minutes

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Total minutes

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Decimal hours

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Handles overnight spans automatically — if end time is earlier than start time, the calculation wraps past midnight.

Quick presets